Merge branch 'develop' of git://github.com/EllisLab/CodeIgniter into develop

49 files changed, 3681 insertions, 1498 deletions

diff --git a/system/core/CodeIgniter.php b/system/core/CodeIgniter.php
index 1cd6403bf..89081b572 100644
--- a/system/core/CodeIgniter.php
+++ b/system/core/CodeIgniter.php
@@ -295,7 +295,11 @@ defined('BASEPATH') OR exit('No direct script access allowed');
 	}
 	else
 	{
-		if ( ! is_callable(array($class, $method)))
+		// WARNING: It appears that there are issues with is_callable() even in PHP 5.2!
+		// Furthermore, there are bug reports and feature/change requests related to it
+		// that make it unreliable to use in this context. Please, DO NOT change this
+		// work-around until a better alternative is available.
+		if ( ! in_array(strtolower($method), array_map('strtolower', get_class_methods($class)), TRUE))
 		{
 			if (empty($RTR->routes['404_override']))
 			{
diff --git a/system/core/Controller.php b/system/core/Controller.php
index cbdf0515f..ee6fec8d5 100644
--- a/system/core/Controller.php
+++ b/system/core/Controller.php
@@ -65,6 +65,7 @@ class CI_Controller {
 		}
 
 		$this->load =& load_class('Loader', 'core');
+		$this->load->initialize();
 		log_message('debug', 'Controller Class Initialized');
 	}
 
diff --git a/system/core/Input.php b/system/core/Input.php
index 142e2b434..c0158df99 100644
--- a/system/core/Input.php
+++ b/system/core/Input.php
@@ -691,7 +691,7 @@ class CI_Input {
 	 */
 	protected function _clean_input_keys($str)
 	{
-		if ( ! preg_match('/^[a-z0-9:_\/-]+$/i', $str))
+		if ( ! preg_match('/^[a-z0-9:_\/|-]+$/i', $str))
 		{
 			set_status_header(503);
 			exit('Disallowed Key Characters.');
diff --git a/system/core/Loader.php b/system/core/Loader.php
index 2a78f4153..808fa80df 100644
--- a/system/core/Loader.php
+++ b/system/core/Loader.php
@@ -130,10 +130,8 @@ class CI_Loader {
 	/**
 	 * Class constructor
 	 *
-	 * Sets component load paths, gets the initial output buffering level
-	 * and calls the autoloader.
+	 * Sets component load paths, gets the initial output buffering level.
 	 *
-	 * @uses	CI_Loader::_ci_autoloader()
 	 * @return	void
 	 */
 	public function __construct()
@@ -143,8 +141,6 @@ class CI_Loader {
 		$this->_ci_helper_paths = array(APPPATH, BASEPATH);
 		$this->_ci_model_paths = array(APPPATH);
 		$this->_ci_view_paths = array(VIEWPATH	=> TRUE);
-		$this->_base_classes =& is_loaded();
-		$this->_ci_autoloader();
 
 		log_message('debug', 'Loader Class Initialized');
 	}
@@ -152,6 +148,23 @@ class CI_Loader {
 	// --------------------------------------------------------------------
 
 	/**
+	 * Initializer
+	 *
+	 * @todo	Figure out a way to move this to the constructor
+	 *		without breaking *package_path*() methods.
+	 * @uses	CI_Loader::_ci_autoloader()
+	 * @used-by	CI_Controller::__construct()
+	 * @return	void
+	 */
+	public function initialize()
+	{
+		$this->_base_classes =& is_loaded();
+		$this->_ci_autoloader();
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
 	 * Is Loaded
 	 *
 	 * A utility method to test if a class is in the self::$_ci_classes array.
@@ -379,7 +392,20 @@ class CI_Loader {
 
 		require_once(BASEPATH.'database/DB_forge.php');
 		require_once(BASEPATH.'database/drivers/'.$CI->db->dbdriver.'/'.$CI->db->dbdriver.'_forge.php');
-		$class = 'CI_DB_'.$CI->db->dbdriver.'_forge';
+
+		if ( ! empty($CI->db->subdriver))
+		{
+			$driver_path = BASEPATH.'database/drivers/'.$CI->db->dbdriver.'/subdrivers/'.$CI->db->dbdriver.'_'.$CI->db->subdriver.'_forge.php';
+			if (file_exists($driver_path))
+			{
+				require_once($driver_path);
+				$class = 'CI_DB_'.$CI->db->dbdriver.'_'.$CI->db->subdriver.'_forge';
+			}
+		}
+		else
+		{
+			$class = 'CI_DB_'.$CI->db->dbdriver.'_forge';
+		}
 
 		$CI->dbforge = new $class();
 	}
@@ -1134,7 +1160,7 @@ class CI_Loader {
 	 *
 	 * Loads component listed in the config/autoload.php file.
 	 *
-	 * @used-by	CI_Loader::__construct()
+	 * @used-by	CI_Loader::initialize()
 	 * @return	void
 	 */
 	protected function _ci_autoloader()
diff --git a/system/core/Router.php b/system/core/Router.php
index 67e9b300d..30bf39657 100644
--- a/system/core/Router.php
+++ b/system/core/Router.php
@@ -147,7 +147,7 @@ class CI_Router {
 
 		// Set the default controller so we can display it in the event
 		// the URI doesn't correlated to a valid controller.
-		$this->default_controller = empty($this->routes['default_controller']) ? FALSE : strtolower($this->routes['default_controller']);
+		$this->default_controller = empty($this->routes['default_controller']) ? FALSE : $this->routes['default_controller'];
 
 		// Were there any query string segments? If so, we'll validate them and bail out since we're done.
 		if (count($segments) > 0)
diff --git a/system/database/DB_forge.php b/system/database/DB_forge.php
index d2d99ccea..2b9fb169a 100644
--- a/system/database/DB_forge.php
+++ b/system/database/DB_forge.php
@@ -36,6 +36,13 @@ defined('BASEPATH') OR exit('No direct script access allowed');
 abstract class CI_DB_forge {
 
 	/**
+	 * Database object
+	 *
+	 * @var	object
+	 */
+	public $db;
+
+	/**
 	 * Fields data
 	 *
 	 * @var	array
@@ -80,23 +87,68 @@ abstract class CI_DB_forge {
 	protected $_drop_database	= 'DROP DATABASE %s';
 
 	/**
-	 * DROP TABLE statement
+	 * CREATE TABLE statement
+	 *
+	 * @var	string
+	 */
+	protected $_create_table	= "%s %s (%s\n)";
+
+	/**
+	 * CREATE TABLE IF statement
+	 *
+	 * @var	string
+	 */
+	protected $_create_table_if	= 'CREATE TABLE IF NOT EXISTS';
+
+	/**
+	 * CREATE TABLE keys flag
+	 *
+	 * Whether table keys are created from within the
+	 * CREATE TABLE statement.
+	 *
+	 * @var	bool
+	 */
+	protected $_create_table_keys	= FALSE;
+
+	/**
+	 * DROP TABLE IF EXISTS statement
 	 *
 	 * @var	string
 	 */
-	protected $_drop_table		= 'DROP TABLE IF EXISTS %s';
+	protected $_drop_table_if	= 'DROP TABLE IF EXISTS';
 
 	/**
 	 * RENAME TABLE statement
 	 *
 	 * @var	string
 	 */
-	protected $_rename_table	= 'ALTER TABLE %s RENAME TO %s';
+	protected $_rename_table	= 'ALTER TABLE %s RENAME TO %s;';
+
+	/**
+	 * UNSIGNED support
+	 *
+	 * @var	bool|array
+	 */
+	protected $_unsigned		= TRUE;
+
+	/**
+	 * NULL value representatin in CREATE/ALTER TABLE statements
+	 *
+	 * @var	string
+	 */
+	protected $_null		= '';
+
+	/**
+	 * DEFAULT value representation in CREATE/ALTER TABLE statements
+	 *
+	 * @var	string
+	 */
+	protected $_default		= ' DEFAULT ';
 
 	// --------------------------------------------------------------------
 
 	/**
-	 * Constructor
+	 * Class constructor
 	 *
 	 * @return	void
 	 */
@@ -113,7 +165,7 @@ abstract class CI_DB_forge {
 	/**
 	 * Create database
 	 *
-	 * @param	string	the database name
+	 * @param	string	$db_name
 	 * @return	bool
 	 */
 	public function create_database($db_name)
@@ -140,7 +192,7 @@ abstract class CI_DB_forge {
 	/**
 	 * Drop database
 	 *
-	 * @param	string	the database name
+	 * @param	string	$db_name
 	 * @return	bool
 	 */
 	public function drop_database($db_name)
@@ -176,25 +228,25 @@ abstract class CI_DB_forge {
 	/**
 	 * Add Key
 	 *
-	 * @param	string	key
-	 * @param	string	type
+	 * @param	string	$key
+	 * @param	bool	$primary
 	 * @return	object
 	 */
 	public function add_key($key = '', $primary = FALSE)
 	{
-		if (is_array($key))
+		if (empty($key))
+		{
+			show_error('Key information is required for that operation.');
+		}
+
+		if ($primary === TRUE && is_array($key))
 		{
 			foreach ($key as $one)
 			{
 				$this->add_key($one, $primary);
 			}
 
-			return;
-		}
-
-		if ($key === '')
-		{
-			show_error('Key information is required for that operation.');
+			return $this;
 		}
 
 		if ($primary === TRUE)
@@ -214,12 +266,12 @@ abstract class CI_DB_forge {
 	/**
 	 * Add Field
 	 *
-	 * @param	string	collation
+	 * @param	array	$field
 	 * @return	object
 	 */
 	public function add_field($field = '')
 	{
-		if ($field === '')
+		if (empty($field))
 		{
 			show_error('Field information is required.');
 		}
@@ -261,8 +313,8 @@ abstract class CI_DB_forge {
 	/**
 	 * Create Table
 	 *
-	 * @param	string	$table = ''
-	 * @param	bool	$if_not_exists = FALSE
+	 * @param	string	$table		Table name
+	 * @param	bool	$if_not_exists	Whether to add IF NOT EXISTS condition
 	 * @return	bool
 	 */
 	public function create_table($table = '', $if_not_exists = FALSE)
@@ -271,51 +323,129 @@ abstract class CI_DB_forge {
 		{
 			show_error('A table name is required for that operation.');
 		}
+		else
+		{
+			$table = $this->db->dbprefix.$table;
+		}
 
 		if (count($this->fields) === 0)
 		{
 			show_error('Field information is required.');
 		}
 
-		$sql = $this->_create_table($this->db->dbprefix.$table, $this->fields, $this->primary_keys, $this->keys, $if_not_exists);
-		$this->_reset();
+		$sql = $this->_create_table($table, $if_not_exists);
 
 		if (is_bool($sql))
 		{
-			return $sql;
+			$this->_reset();
+			if ($sql === FALSE)
+			{
+				return ($this->db->db_debug) ? $this->db->display_error('db_unsuported_feature') : FALSE;
+			}
 		}
 
-		if (($result = $this->db->query($sql)) !== FALSE && ! empty($this->db->data_cache['table_names']))
+		if (($result = $this->db->query($sql)) !== FALSE)
 		{
-			$this->db->data_cache['table_names'][] = $this->db->dbprefix.$table;
+			empty($this->db->data_cache['table_names']) OR $this->db->data_cache['table_names'][] = $table;
+
+			// Most databases don't support creating indexes from within the CREATE TABLE statement
+			if ( ! empty($this->keys))
+			{
+				for ($i = 0, $sqls = $this->_process_indexes($table), $c = count($sqls); $i < $c; $i++)
+				{
+					$this->db->query($sqls[$i]);
+				}
+			}
 		}
 
+		$this->_reset();
 		return $result;
 	}
 
 	// --------------------------------------------------------------------
 
 	/**
+	 * Create Table
+	 *
+	 * @param	string	$table		Table name
+	 * @param	bool	$if_not_exists	Whether to add 'IF NOT EXISTS' condition
+	 * @return	mixed
+	 */
+	protected function _create_table($table, $if_not_exists)
+	{
+		if ($if_not_exists === TRUE && $this->_create_table_if === FALSE)
+		{
+			if ($this->db->table_exists($table))
+			{
+				return TRUE;
+			}
+			else
+			{
+				$if_not_exists = FALSE;
+			}
+		}
+
+		$sql = ($if_not_exists)
+			? sprintf($this->_create_table_if, $this->db->escape_identifiers($table))
+			: 'CREATE TABLE';
+
+		$columns = $this->_process_fields(TRUE);
+		for ($i = 0, $c = count($columns); $i < $c; $i++)
+		{
+			$columns[$i] = ($columns[$i]['_literal'] !== FALSE)
+					? "\n\t".$columns[$i]['_literal']
+					: "\n\t".$this->_process_column($columns[$i]);
+		}
+
+		$columns = implode(',', $columns)
+				.$this->_process_primary_keys($table);
+
+		// Are indexes created from within the CREATE TABLE statement? (e.g. in MySQL)
+		if ($this->_create_table_keys === TRUE)
+		{
+			$columns .= $this->_process_indexes();
+		}
+
+		// _create_table will usually have the following format: "%s %s (%s\n)"
+		$sql = sprintf($this->_create_table.';',
+			$sql,
+			$this->db->escape_identifiers($table),
+			$columns
+		);
+
+		return $sql;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
 	 * Drop Table
 	 *
-	 * @param	string	the table name
+	 * @param	string	$table_name	Table name
+	 * @param	bool	$if_exists	Whether to add an IF EXISTS condition
 	 * @return	bool
 	 */
-	public function drop_table($table_name)
+	public function drop_table($table_name, $if_exists = FALSE)
 	{
 		if ($table_name === '')
 		{
 			return ($this->db->db_debug) ? $this->db->display_error('db_table_name_required') : FALSE;
 		}
-		elseif ($this->_drop_table === FALSE)
+
+		$query = $this->_drop_table($this->db->dbprefix.$table_name, $if_exists);
+		if ($query === FALSE)
 		{
 			return ($this->db->db_debug) ? $this->db->display_error('db_unsuported_feature') : FALSE;
 		}
+		elseif ($query === TRUE)
+		{
+			return TRUE;
+		}
 
-		$result = $this->db->query(sprintf($this->_drop_table, $this->db->escape_identifiers($this->db->dbprefix.$table_name)));
+		$query = $this->db->query($query);
 
 		// Update table list cache
-		if ($result && ! empty($this->db->data_cache['table_names']))
+		if ($query && ! empty($this->db->data_cache['table_names']))
 		{
 			$key = array_search(strtolower($this->db->dbprefix.$table_name), array_map('strtolower', $this->db->data_cache['table_names']), TRUE);
 			if ($key !== FALSE)
@@ -324,7 +454,40 @@ abstract class CI_DB_forge {
 			}
 		}
 
-		return $result;
+		return $query;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Drop Table
+	 *
+	 * Generates a platform-specific DROP TABLE string
+	 *
+	 * @param	string	$table		Table name
+	 * @param	bool	$if_exists	Whether to add an IF EXISTS condition
+	 * @return	string
+	 */
+	protected function _drop_table($table, $if_exists)
+	{
+		$sql = 'DROP TABLE';
+
+		if ($if_exists)
+		{
+			if ($this->_drop_table_if === FALSE)
+			{
+				if ( ! $this->db->table_exists($table))
+				{
+					return TRUE;
+				}
+			}
+			else
+			{
+				$sql = sprintf($this->_drop_table_if, $this->db->escape_identifiers($table));
+			}
+		}
+
+		return $sql.' '.$this->db->escape_identifiers($table);
 	}
 
 	// --------------------------------------------------------------------
@@ -332,8 +495,8 @@ abstract class CI_DB_forge {
 	/**
 	 * Rename Table
 	 *
-	 * @param	string	the old table name
-	 * @param	string	the new table name
+	 * @param	string	$table_name	Old table name
+	 * @param	string	$new_table_name	New table name
 	 * @return	bool
 	 */
 	public function rename_table($table_name, $new_table_name)
@@ -370,33 +533,38 @@ abstract class CI_DB_forge {
 	/**
 	 * Column Add
 	 *
-	 * @param	string	the table name
-	 * @param	string	the column name
-	 * @param	string	the column definition
+	 * @param	string	$table	Table name
+	 * @param	array	$field	Column definition
 	 * @return	bool
 	 */
-	public function add_column($table = '', $field = array(), $after_field = '')
+	public function add_column($table = '', $field = array())
 	{
 		if ($table === '')
 		{
 			show_error('A table name is required for that operation.');
 		}
 
-		// add field info into field array, but we can only do one at a time
-		// so we cycle through
+		// Work-around for literal column definitions
+		if ( ! is_array($field))
+		{
+			$field = array($field);
+		}
+
 		foreach (array_keys($field) as $k)
 		{
 			$this->add_field(array($k => $field[$k]));
+		}
 
-			if (count($this->fields) === 0)
-			{
-				show_error('Field information is required.');
-			}
-
-			$sql = $this->_alter_table('ADD', $this->db->dbprefix.$table, $this->fields, $after_field);
-			$this->_reset();
+		$sqls = $this->_alter_table('ADD', $this->db->dbprefix.$table, $this->_process_fields());
+		$this->_reset();
+		if ($sqls === FALSE)
+		{
+			return ($this->db->db_debug) ? $this->db->display_error('db_unsuported_feature') : FALSE;
+		}
 
-			if ($this->db->query($sql) === FALSE)
+		for ($i = 0, $c = count($sqls); $i < $c; $i++)
+		{
+			if ($this->db->query($sqls[$i]) === FALSE)
 			{
 				return FALSE;
 			}
@@ -410,8 +578,8 @@ abstract class CI_DB_forge {
 	/**
 	 * Column Drop
 	 *
-	 * @param	string	the table name
-	 * @param	string	the column name
+	 * @param	string	$table		Table name
+	 * @param	string	$column_name	Column name
 	 * @return	bool
 	 */
 	public function drop_column($table = '', $column_name = '')
@@ -426,7 +594,13 @@ abstract class CI_DB_forge {
 			show_error('A column name is required for that operation.');
 		}
 
-		return $this->db->query($this->_alter_table('DROP', $this->db->dbprefix.$table, $column_name));
+		$sql = $this->_alter_table('DROP', $this->db->dbprefix.$table, $column_name);
+		if ($sql === FALSE)
+		{
+			return ($this->db->db_debug) ? $this->db->display_error('db_unsuported_feature') : FALSE;
+		}
+
+		return $this->db->query($sql);
 	}
 
 	// --------------------------------------------------------------------
@@ -434,8 +608,8 @@ abstract class CI_DB_forge {
 	/**
 	 * Column Modify
 	 *
-	 * @param	string	$table = ''
-	 * @param	string	$field = array()	column definition
+	 * @param	string	$table	Table name
+	 * @param	string	$field	Column definition
 	 * @return	bool
 	 */
 	public function modify_column($table = '', $field = array())
@@ -445,32 +619,363 @@ abstract class CI_DB_forge {
 			show_error('A table name is required for that operation.');
 		}
 
-		// add field info into field array, but we can only do one at a time
-		// so we cycle through
+		// Work-around for literal column definitions
+		if ( ! is_array($field))
+		{
+			$field = array($field);
+		}
+
 		foreach (array_keys($field) as $k)
 		{
-			// If no name provided, use the current name
-			if ( ! isset($field[$k]['name']))
+			$this->add_field(array($k => $field[$k]));
+		}
+
+		if (count($this->fields) === 0)
+		{
+			show_error('Field information is required.');
+		}
+
+		$sqls = $this->_alter_table('CHANGE', $this->db->dbprefix.$table, $this->fields);
+		$this->_reset();
+		if ($sqls === FALSE)
+		{
+			return ($this->db->db_debug) ? $this->db->display_error('db_unsuported_feature') : FALSE;
+		}
+
+		for ($i = 0, $c = count($sqls); $i < $c; $i++)
+		{
+			if ($this->db->query($sqls[$i]) === FALSE)
 			{
-				$field[$k]['name'] = $k;
+				return FALSE;
 			}
+		}
 
-			$this->add_field(array($k => $field[$k]));
-			if (count($this->fields) === 0)
+		return TRUE;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * ALTER TABLE
+	 *
+	 * @param	string	$alter_type	ALTER type
+	 * @param	string	$table		Table name
+	 * @param	mixed	$field		Column definition
+	 * @return	string|string[]
+	 */
+	protected function _alter_table($alter_type, $table, $field)
+	{
+		$sql = 'ALTER TABLE '.$this->db->escape_identifiers($table).' ';
+
+		// DROP has everything it needs now.
+		if ($alter_type === 'DROP')
+		{
+			return $sql.'DROP COLUMN '.$this->db->escape_identifiers($field);
+		}
+
+		$sqls = array();
+		for ($i = 0, $c = count($field), $sql .= $alter_type.' COLUMN '; $i < $c; $i++)
+		{
+			$sqls[] = $sql
+				.($field[$i]['_literal'] !== FALSE ? $field[$i]['_literal'] : $this->_process_column($field[$i]));
+		}
+
+		return $sqls;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Process fields
+	 *
+	 * @param	bool	$create_table
+	 * @return	array
+	 */
+	protected function _process_fields($create_table = FALSE)
+	{
+		$fields = array();
+
+		foreach ($this->fields as $key => $attributes)
+		{
+			if (is_int($key) && ! is_array($attributes))
 			{
-				show_error('Field information is required.');
+				$fields[] = array('_literal' => $attributes);
+				continue;
 			}
 
-			$sql = $this->_alter_table('CHANGE', $this->db->dbprefix.$table, $this->fields);
-			$this->_reset();
+			$attributes = array_change_key_case($attributes, CASE_UPPER);
 
-			if ($this->db->query($sql) === FALSE)
+			if ($create_table === TRUE && empty($attributes['TYPE']))
 			{
-				return FALSE;
+				continue;
 			}
+
+			if (isset($attributes['TYPE']))
+			{
+				$this->_attr_type($attributes);
+				$this->_attr_unsigned($attributes, $field);
+			}
+
+			$field = array(
+					'name'			=> $key,
+					'new_name'		=> isset($attributes['NAME']) ? $attributes['NAME'] : NULL,
+					'type'			=> isset($attributes['TYPE']) ? $attributes['TYPE'] : NULL,
+					'length'		=> '',
+					'unsigned'		=> '',
+					'null'			=> '',
+					'unique'		=> '',
+					'default'		=> '',
+					'auto_increment'	=> '',
+					'_literal'		=> FALSE
+			);
+
+			$this->_attr_default($attributes, $field);
+
+			if (isset($attributes['NULL']))
+			{
+				if ($attributes['NULL'] === TRUE)
+				{
+					$field['null'] = empty($this->_null) ? '' : ' '.$this->_null;
+				}
+				elseif ($create_table === TRUE)
+				{
+					$field['null'] = ' NOT NULL';
+				}
+			}
+
+			$this->_attr_auto_increment($attributes, $field);
+			$this->_attr_unique($attributes, $field);
+
+			if (isset($attributes['TYPE']) && ! empty($attributes['CONSTRAINT']))
+			{
+				switch (strtoupper($attributes['TYPE']))
+				{
+					case 'ENUM':
+					case 'SET':
+						$attributes['CONSTRAINT'] = $this->db->escape($attributes['CONSTRAINT']);
+					default:
+						$field['length'] = is_array($attributes['CONSTRAINT'])
+								? '('.implode(',', $attributes['CONSTRAINT']).')'
+								: '('.$attributes['CONSTRAINT'].')';
+						break;
+				}
+			}
+
+			$fields[] = $field;
 		}
 
-		return TRUE;
+		return $fields;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Process column
+	 *
+	 * @param	array	$field
+	 * @return	string
+	 */
+	protected function _process_column($field)
+	{
+		return $this->db->escape_identifiers($field['name'])
+			.' '.$field['type'].$field['length']
+			.$field['unsigned']
+			.$field['default']
+			.$field['null']
+			.$field['auto_increment']
+			.$field['unique'];
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute TYPE
+	 *
+	 * Performs a data type mapping between different databases.
+	 *
+	 * @param	array	&$attributes
+	 * @return	void
+	 */
+	protected function _attr_type(&$attributes)
+	{
+		// Usually overriden by drivers
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute UNSIGNED
+	 *
+	 * Depending on the _unsigned property value:
+	 *
+	 *	- TRUE will always set $field['unsigned'] to 'UNSIGNED'
+	 *	- FALSE will always set $field['unsigned'] to ''
+	 *	- array(TYPE) will set $field['unsigned'] to 'UNSIGNED',
+	 *		if $attributes['TYPE'] is found in the array
+	 *	- array(TYPE => UTYPE) will change $field['type'],
+	 *		from TYPE to UTYPE in case of a match
+	 *
+	 * @param	array	&$attributes
+	 * @param	array	&$field
+	 * @return	void
+	 */
+	protected function _attr_unsigned(&$attributes, &$field)
+	{
+		if (empty($attributes['UNSIGNED']) OR $attributes['UNSIGNED'] !== TRUE)
+		{
+			return;
+		}
+
+		// Reset the attribute in order to avoid issues if we do type conversion
+		$attributes['UNSIGNED'] = FALSE;
+
+		if (is_array($this->_unsigned))
+		{
+			foreach (array_keys($this->_unsigned) as $key)
+			{
+				if (is_int($key) && strcasecmp($attributes['TYPE'], $this->_unsigned[$key]) === 0)
+				{
+					$field['unsigned'] = ' UNSIGNED';
+					return;
+				}
+				elseif (is_string($key) && strcasecmp($attributes['TYPE'], $key) === 0)
+				{
+					$field['type'] = $key;
+					return;
+				}
+			}
+
+			return;
+		}
+
+		$field['unsigned'] = ($this->_unsigned === TRUE) ? ' UNSIGNED' : '';
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute DEFAULT
+	 *
+	 * @param	array	&$attributes
+	 * @param	array	&$field
+	 * @return	void
+	 */
+	protected function _attr_default(&$attributes, &$field)
+	{
+		if ($this->_default === FALSE)
+		{
+			return;
+		}
+
+		if (array_key_exists('DEFAULT', $attributes))
+		{
+			if ($attributes['DEFAULT'] === NULL)
+			{
+				$field['default'] = empty($this->_null) ? '' : $this->_default.$this->_null;
+
+				// Override the NULL attribute if that's our default
+				$attributes['NULL'] = NULL;
+				$field['null'] = empty($this->_null) ? '' : ' '.$this->_null;
+			}
+			else
+			{
+				$field['default'] = $this->_default.$this->db->escape($attributes['DEFAULT']);
+			}
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute UNIQUE
+	 *
+	 * @param	array	&$attributes
+	 * @param	array	&$field
+	 * @return	void
+	 */
+	protected function _attr_unique(&$attributes, &$field)
+	{
+		if ( ! empty($attributes['UNIQUE']) && $attributes['UNIQUE'] === TRUE)
+		{
+			$field['unique'] = ' UNIQUE';
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute AUTO_INCREMENT
+	 *
+	 * @param	array	&$attributes
+	 * @param	array	&$field
+	 * @return	void
+	 */
+	protected function _attr_auto_increment(&$attributes, &$field)
+	{
+		if ( ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE && stripos($field['type'], 'int') !== FALSE)
+		{
+			$field['auto_increment'] = ' AUTO_INCREMENT';
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Process primary keys
+	 *
+	 * @param	string	$table	Table name
+	 * @return	string
+	 */
+	protected function _process_primary_keys($table)
+	{
+		$sql = '';
+
+		for ($i = 0, $c = count($this->primary_keys); $i < $c; $i++)
+		{
+			if ( ! isset($this->fields[$this->primary_keys[$i]]))
+			{
+				unset($this->primary_keys[$i]);
+			}
+		}
+
+		if (count($this->primary_keys) > 0)
+		{
+			$sql .= ",\n\tCONSTRAINT ".$this->db->escape_identifiers('pk_'.$table)
+				.' PRIMARY KEY('.implode(', ', $this->db->escape_identifiers($this->primary_keys)).')';
+		}
+
+		return $sql;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Process indexes
+	 *
+	 * @param	string	$table
+	 * @return	string
+	 */
+	protected function _process_indexes($table = NULL)
+	{
+		$table = $this->db->escape_identifiers($table);
+		$sqls = array();
+
+		for ($i = 0, $c = count($this->keys); $i < $c; $i++)
+		{
+			if ( ! isset($this->fields[$this->keys[$i]]))
+			{
+				unset($this->keys[$i]);
+				continue;
+			}
+
+			is_array($this->keys[$i]) OR $this->keys[$i] = array($this->keys[$i]);
+
+			$sqls[] = 'CREATE INDEX '.$this->db->escape_identifiers(implode('_', $this->keys[$i]))
+				.' ON '.$this->db->escape_identifiers($table)
+				.' ('.implode(', ', $this->db->escape_identifiers($this->keys[$i])).');';
+		}
+
+		return $sqls;
 	}
 
 	// --------------------------------------------------------------------
diff --git a/system/database/drivers/cubrid/cubrid_driver.php b/system/database/drivers/cubrid/cubrid_driver.php
index 48b904286..c89a924d3 100644
--- a/system/database/drivers/cubrid/cubrid_driver.php
+++ b/system/database/drivers/cubrid/cubrid_driver.php
@@ -179,9 +179,18 @@ class CI_DB_cubrid_driver extends CI_DB {
 	 */
 	public function version()
 	{
-		return isset($this->data_cache['version'])
-			? $this->data_cache['version']
-			: $this->data_cache['version'] = cubrid_get_server_info($this->conn_id);
+		if (isset($this->data_cache['version']))
+		{
+			return $this->data_cache['version'];
+		}
+		elseif ( ! $this->conn_id)
+		{
+			$this->initialize();
+		}
+
+		return ( ! $this->conn_id OR ($version = cubrid_get_server_info($this->conn_id)) === FALSE)
+			? FALSE
+			: $this->data_cache['version'] = $version;
 	}
 
 	// --------------------------------------------------------------------
diff --git a/system/database/drivers/cubrid/cubrid_forge.php b/system/database/drivers/cubrid/cubrid_forge.php
index 33d502137..e3f8bc334 100644
--- a/system/database/drivers/cubrid/cubrid_forge.php
+++ b/system/database/drivers/cubrid/cubrid_forge.php
@@ -42,8 +42,6 @@ class CI_DB_cubrid_forge extends CI_DB_forge {
 	 */
 	protected $_create_database	= FALSE;
 
-	// --------------------------------------------------------------------
-
 	/**
 	 * DROP DATABASE statement
 	 *
@@ -52,177 +50,121 @@ class CI_DB_cubrid_forge extends CI_DB_forge {
 	protected $_drop_database	= FALSE;
 
 	/**
-	 * Process Fields
+	 * CREATE TABLE IF statement
 	 *
-	 * @param	mixed	$fields
-	 * @return	string
+	 * @var	string
+	 */
+	protected $_create_table_if	= FALSE;
+
+	/**
+	 * UNSIGNED support
+	 *
+	 * @var	array
 	 */
-	protected function _process_fields($fields)
+	protected $_unsigned		= array(
+		'SHORT'		=> 'INTEGER',
+		'SMALLINT'	=> 'INTEGER',
+		'INT'		=> 'BIGINT',
+		'INTEGER'	=> 'BIGINT',
+		'BIGINT'	=> 'NUMERIC',
+		'FLOAT'		=> 'DOUBLE',
+		'REAL'		=> 'DOUBLE'
+	);
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * ALTER TABLE
+	 *
+	 * @param	string	$alter_type	ALTER type
+	 * @param	string	$table		Table name
+	 * @param	mixed	$field		Column definition
+	 * @return	string|string[]
+	 */
+	protected function _alter_table($alter_type, $table, $field)
 	{
-		$current_field_count = 0;
-		$sql = '';
+		if (in_array($alter_type, array('DROP', 'ADD'), TRUE))
+		{
+			return parent::_alter_table($alter_type, $table, $field);
+		}
 
-		foreach ($fields as $field => $attributes)
+		$sql = 'ALTER TABLE '.$this->db->escape_identifiers($table);
+		$sqls = array();
+		for ($i = 0, $c = count($field); $i < $c; $i++)
 		{
-			// Numeric field names aren't allowed in databases, so if the key is
-			// numeric, we know it was assigned by PHP and the developer manually
-			// entered the field information, so we'll simply add it to the list
-			if (is_numeric($field))
+			if ($field[$i]['_literal'] !== FALSE)
 			{
-				$sql .= "\n\t".$attributes;
+				$sqls[] = $sql.' CHANGE '.$field[$i]['_literal'];
 			}
 			else
 			{
-				$attributes = array_change_key_case($attributes, CASE_UPPER);
-
-				$sql .= "\n\t".$this->db->escape_identifiers($field);
-
-				empty($attributes['NAME']) OR $sql .= ' '.$this->db->escape_identifiers($attributes['NAME']).' ';
-
-				if ( ! empty($attributes['TYPE']))
-				{
-					$sql .= ' '.$attributes['TYPE'];
-
-					if ( ! empty($attributes['CONSTRAINT']))
-					{
-						switch (strtolower($attributes['TYPE']))
-						{
-							case 'decimal':
-							case 'float':
-							case 'numeric':
-								$sql .= '('.implode(',', $attributes['CONSTRAINT']).')';
-								break;
-							case 'enum':
-								// Will be supported in the future as part a part of
-								// MySQL compatibility features.
-								break;
-							case 'set':
-								$sql .= '("'.implode('","', $attributes['CONSTRAINT']).'")';
-								break;
-							default:
-								$sql .= '('.$attributes['CONSTRAINT'].')';
-						}
-					}
-				}
-
-			/* As of version 8.4.1 CUBRID does not support UNSIGNED INTEGER data type.
-			 * Will be supported in the next release as a part of MySQL Compatibility.
-			 *
-				if (isset($attributes['UNSIGNED']) && $attributes['UNSIGNED'] === TRUE)
-				{
-					$sql .= ' UNSIGNED';
-				}
-			 */
-
-				if (isset($attributes['DEFAULT']))
-				{
-					$sql .= " DEFAULT '".$attributes['DEFAULT']."'";
-				}
-
-				$sql .= ( ! empty($attributes['NULL']) && $attributes['NULL'] === TRUE)
-					? ' NULL' : ' NOT NULL';
-
-				if ( ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE)
-				{
-					$sql .= ' AUTO_INCREMENT';
-				}
-
-				if ( ! empty($attributes['UNIQUE']) && $attributes['UNIQUE'] === TRUE)
+				$sqls[] = $sql.' CHANGE '.$this->_process_column($field[$i]);
+				if ( ! empty($field[$i]['new_name']))
 				{
-					$sql .= ' UNIQUE';
+					$sqls[] = $sql.' RENAME COLUMN '.$this->db->escape_identifiers($field[$i]['name'])
+						.' AS '.$this->db->escape_identifiers($field[$i]['name']);
 				}
 			}
-
-			// don't add a comma on the end of the last field
-			if (++$current_field_count < count($fields))
-			{
-				$sql .= ',';
-			}
 		}
 
-		return $sql;
+		return $sqls;
 	}
 
 	// --------------------------------------------------------------------
 
 	/**
-	 * Create Table
+	 * Field attribute TYPE
 	 *
-	 * @param	string	the table name
-	 * @param	mixed	the fields
-	 * @param	mixed	primary key(s)
-	 * @param	mixed	key(s)
-	 * @param	bool	should 'IF NOT EXISTS' be added to the SQL
-	 * @return	bool
+	 * Performs a data type mapping between different databases.
+	 *
+	 * @param	array	&$attributes
+	 * @return	void
 	 */
-	protected function _create_table($table, $fields, $primary_keys, $keys, $if_not_exists)
+	protected function _attr_type(&$attributes)
 	{
-		$sql = 'CREATE TABLE ';
-
-		/* As of version 8.4.1 CUBRID does not support this SQL syntax.
-		if ($if_not_exists === TRUE)
+		switch (strtoupper($attributes['TYPE']))
 		{
-			$sql .= 'IF NOT EXISTS ';
+			case 'TINYINT':
+				$attributes['TYPE'] = 'SMALLINT';
+				$attributes['UNSIGNED'] = FALSE;
+				return;
+			case 'MEDIUMINT':
+				$attributes['TYPE'] = 'INTEGER';
+				$attributes['UNSIGNED'] = FALSE;
+				return;
+			default: return;
 		}
-		*/
-
-		$sql .= $this->db->escape_identifiers($table).' ('.$this->_process_fields($fields);
-
-		// If there is a PK defined
-		if (count($primary_keys) > 0)
-		{
-			$key_name = $this->db->escape_identifiers('pk_'.$table.'_'.implode('_', $primary_keys));
-			$sql .= ",\n\tCONSTRAINT ".$key_name.' PRIMARY KEY('.implode(', ', $this->db->escape_identifiers($primary_keys)).')';
-		}
-
-		if (is_array($keys) && count($keys) > 0)
-		{
-			foreach ($keys as $key)
-			{
-				if (is_array($key))
-				{
-					$key_name = $this->db->escape_identifiers('idx_'.$table.implode('_', $key));
-					$key = $this->db->escape_identifiers($key);
-				}
-				else
-				{
-					$key_name = $this->db->escape_identifiers('idx_'.$table.$key);
-					$key = array($key_name);
-				}
-
-				$sql .= ",\n\tKEY ".$key_name.' ('.implode(', ', $key).')';
-			}
-		}
-
-		return $sql."\n);";
 	}
 
 	// --------------------------------------------------------------------
 
 	/**
-	 * Alter table query
-	 *
-	 * Generates a platform-specific query so that a table can be altered
-	 * Called by add_column(), drop_column(), and column_alter(),
+	 * Process indexes
 	 *
-	 * @param	string	the ALTER type (ADD, DROP, CHANGE)
-	 * @param	string	the column name
-	 * @param	array	fields
-	 * @param	string	the field after which we should add the new field
+	 * @param	string	$table	(ignored)
 	 * @return	string
 	 */
-	protected function _alter_table($alter_type, $table, $fields, $after_field = '')
+	protected function _process_indexes($table = NULL)
 	{
-		$sql = 'ALTER TABLE '.$this->db->escape_identifiers($table).' '.$alter_type.' ';
+		$sql = '';
 
-		// DROP has everything it needs now.
-		if ($alter_type === 'DROP')
+		for ($i = 0, $c = count($this->keys); $i < $c; $i++)
 		{
-			return $sql.$this->db->escape_identifiers($fields);
+			if ( ! isset($this->fields[$this->keys[$i]]))
+			{
+				unset($this->keys[$i]);
+				continue;
+			}
+
+			is_array($this->keys[$i]) OR $this->keys[$i] = array($this->keys[$i]);
+
+			$sql .= ",\n\tKEY ".$this->db->escape_identifiers(implode('_', $this->keys[$i]))
+				.' ('.implode(', ', $this->db->escape_identifiers($this->keys[$i])).')';
 		}
 
-		return $sql.$this->_process_fields($fields)
-			.($after_field !== '' ? ' AFTER '.$this->db->escape_identifiers($after_field) : '');
+		$this->keys = array();
+
+		return $sql;
 	}
 
 }
diff --git a/system/database/drivers/ibase/ibase_forge.php b/system/database/drivers/ibase/ibase_forge.php
index 7c4d00a23..a0c4e6563 100644
--- a/system/database/drivers/ibase/ibase_forge.php
+++ b/system/database/drivers/ibase/ibase_forge.php
@@ -36,11 +36,43 @@ defined('BASEPATH') OR exit('No direct script access allowed');
 class CI_DB_ibase_forge extends CI_DB_forge {
 
 	/**
-	 * DROP TABLE statement
+	 * CREATE TABLE IF statement
 	 *
 	 * @var	string
 	 */
-	protected $_drop_table	= 'DROP TABLE %s';
+	protected $_create_table_if	= FALSE;
+
+	/**
+	 * RENAME TABLE statement
+	 *
+	 * @var	string
+	 */
+	protected $_rename_table	= FALSE;
+
+	/**
+	 * DROP TABLE IF statement
+	 *
+	 * @var	string
+	 */
+	protected $_drop_table_if	= FALSE;
+
+	/**
+	 * UNSIGNED support
+	 *
+	 * @var	array
+	 */
+	protected $_unsigned		= array(
+		'SMALLINT'	=> 'INTEGER',
+		'INTEGER'	=> 'INT64',
+		'FLOAT'		=> 'DOUBLE PRECISION'
+	);
+
+	/**
+	 * NULL value representation in CREATE/ALTER TABLE statements
+	 *
+	 * @var	string
+	 */
+	protected $_null		= 'NULL';
 
 	// --------------------------------------------------------------------
 
@@ -65,8 +97,7 @@ class CI_DB_ibase_forge extends CI_DB_forge {
 	/**
 	 * Drop database
 	 *
-	 * @param	string	the database name
-	 *		- not used in this driver, the current db is dropped
+	 * @param	string	$db_name	(ignored)
 	 * @return	bool
 	 */
 	public function drop_database($db_name = '')
@@ -90,110 +121,119 @@ class CI_DB_ibase_forge extends CI_DB_forge {
 	// --------------------------------------------------------------------
 
 	/**
-	 * Create Table
+	 * ALTER TABLE
 	 *
-	 * @param	string	the table name
-	 * @param	array	the fields
-	 * @param	mixed	primary key(s)
-	 * @param	mixed	key(s)
-	 * @param	bool	should 'IF NOT EXISTS' be added to the SQL
-	 * @return	string
+	 * @param	string	$alter_type	ALTER type
+	 * @param	string	$table		Table name
+	 * @param	mixed	$field		Column definition
+	 * @return	string|string[]
 	 */
-	protected function _create_table($table, $fields, $primary_keys, $keys, $if_not_exists)
-	{
-		$sql = 'CREATE TABLE ';
-
-		$sql .= $this->db->escape_identifiers($table).'(';
-		$current_field_count = 0;
+	protected function _alter_table($alter_type, $table, $field)
+ 	{
+		if (in_array($alter_type, array('DROP', 'ADD'), TRUE))
+		{
+			return parent::_alter_table($alter_type, $table, $field);
+		}
 
-		foreach ($fields as $field => $attributes)
+		$sql = 'ALTER TABLE '.$this->db->escape_identifiers($table);
+		$sqls = array();
+		for ($i = 0, $c = count($field), $sql .= $alter_type.' '; $i < $c; $i++)
 		{
-			// Numeric field names aren't allowed in databases, so if the key is
-			// numeric, we know it was assigned by PHP and the developer manually
-			// entered the field information, so we'll simply add it to the list
-			if (is_numeric($field))
+			if ($field[$i]['_literal'] !== FALSE)
 			{
-				$sql .= "\n\t".$attributes;
+				return FALSE;
 			}
-			else
-			{
-				$attributes = array_change_key_case($attributes, CASE_UPPER);
-
-				$sql .= "\n\t".$this->db->escape_identifiers($field).' '.$attributes['TYPE'];
-
-				empty($attributes['CONSTRAINT']) OR $sql .= '('.$attributes['CONSTRAINT'].')';
-
-				if ( ! empty($attributes['UNSIGNED']) && $attributes['UNSIGNED'] === TRUE)
-				{
-					$sql .= ' UNSIGNED';
-				}
-
-				if (isset($attributes['DEFAULT']))
-				{
-					$sql .= " DEFAULT '".$attributes['DEFAULT']."'";
-				}
 
-				$sql .= ( ! empty($attributes['NULL']) && $attributes['NULL'] === TRUE)
-					? ' NULL' : ' NOT NULL';
-
-				if ( ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE)
-				{
-					$sql .= ' AUTO_INCREMENT';
-				}
+			if (isset($field[$i]['type']))
+			{
+				$sqls[] = $sql.' TYPE '.$field[$i]['type'].$field[$i]['length'];
 			}
 
-			// don't add a comma on the end of the last field
-			if (++$current_field_count < count($fields))
+			if ( ! empty($field[$i]['default']))
 			{
-				$sql .= ',';
+				$sqls[] = $sql.' ALTER '.$this->db->escape_identifiers($field[$i]['name'])
+					.' SET '.$field[$i]['default'];
 			}
-		}
 
-		if (count($primary_keys) > 0)
-		{
-			$primary_keys = $this->db->escape_identifiers($primary_keys);
-			$sql .= ",\n\tPRIMARY KEY (".implode(', ', $primary_keys).')';
-		}
-
-		if (is_array($keys) && count($keys) > 0)
-		{
-			foreach ($keys as $key)
+			if (isset($field[$i]['null']))
 			{
-				$key = is_array($key)
-					? $this->db->escape_identifiers($key)
-					: array($this->db->escape_identifiers($key));
+				$sqls[] = 'UPDATE "RDB$RELATION_FIELDS" SET "RDB$NULL_FLAG" = '
+					.($field[$i]['null'] === TRUE ? 'NULL' : '1')
+					.' WHERE "RDB$FIELD_NAME" = '.$this->db->escape($field[$i]['name'])
+					.' AND "RDB$RELATION_NAME" = '.$this->db->escape($table);
+			}
 
-				$sql .= ",\n\tUNIQUE (".implode(', ', $key).')';
+			if ( ! empty($field[$i]['new_name']))
+			{
+				$sqls[] = $sql.' ALTER '.$this->db->escape_identifiers($field[$i]['name'])
+					.' TO '.$this->db->escape_identifiers($field[$i]['new_name']);
 			}
 		}
 
-		return $sql."\n)";
+		return $sqls;
+ 	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Process column
+	 *
+	 * @param	array	$field
+	 * @return	string
+	 */
+	protected function _process_column($field)
+	{
+		return $this->db->escape_identifiers($field['name'])
+			.' '.$field['type'].$field['length']
+			.$field['null']
+			.$field['unique']
+			.$field['default'];
 	}
 
 	// --------------------------------------------------------------------
 
 	/**
-	 * Alter table query
+	 * Field attribute TYPE
 	 *
-	 * Generates a platform-specific query so that a table can be altered
-	 * Called by add_column(), drop_column(), and column_alter(),
+	 * Performs a data type mapping between different databases.
 	 *
-	 * @param	string	the ALTER type (ADD, DROP, CHANGE)
-	 * @param	string	the column name
-	 * @param	string	the table name
-	 * @param	string	the column definition
-	 * @param	string	the default value
-	 * @param	bool	should 'NOT NULL' be added
-	 * @param	string	the field after which we should add the new field
-	 * @return	string
+	 * @param	array	&$attributes
+	 * @return	void
+	 */
+	protected function _attr_type(&$attributes)
+	{
+		switch (strtoupper($attributes['TYPE']))
+		{
+			case 'TINYINT':
+				$attributes['TYPE'] = 'SMALLINT';
+				$attributes['UNSIGNED'] = FALSE;
+				return;
+			case 'MEDIUMINT':
+				$attributes['TYPE'] = 'INTEGER';
+				$attributes['UNSIGNED'] = FALSE;
+				return;
+			case 'INT':
+				$attributes['TYPE'] = 'INTEGER';
+				return;
+			case 'BIGINT':
+				$attributes['TYPE'] = 'INT64';
+				return;
+			default: return;
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute AUTO_INCREMENT
+	 *
+	 * @param	array	&$attributes
+	 * @param	array	&$field
+	 * @return	void
 	 */
-	protected function _alter_table($alter_type, $table, $column_name, $column_definition = '', $default_value = '', $null = '', $after_field = '')
+	protected function _attr_auto_increment(&$attributes, &$field)
 	{
-		return 'ALTER TABLE '.$this->db->escape_identifiers($table).' '.$alter_type.' '.$this->db->escape_identifiers($column_name)
-			.' '.$column_definition
-			.($default_value !== '' ? ' DEFAULT "'.$default_value.'"' : '')
-			.($null === NULL ? ' NULL' : ' NOT NULL')
-			.($after_field !== '' ? ' AFTER '.$this->db->escape_identifiers($after_field) : '');
+		// Not supported
 	}
 
 }
diff --git a/system/database/drivers/mssql/mssql_forge.php b/system/database/drivers/mssql/mssql_forge.php
index 1eef648b0..5eebedbf7 100644
--- a/system/database/drivers/mssql/mssql_forge.php
+++ b/system/database/drivers/mssql/mssql_forge.php
@@ -36,130 +36,98 @@ defined('BASEPATH') OR exit('No direct script access allowed');
 class CI_DB_mssql_forge extends CI_DB_forge {
 
 	/**
-	 * DROP TABLE statement
+	 * CREATE TABLE IF statement
 	 *
 	 * @var	string
 	 */
-	protected $_drop_table	= 'DROP TABLE %s';
-
-	// --------------------------------------------------------------------
+	protected $_create_table_if	= "IF NOT EXISTS (SELECT * FROM sysobjects WHERE ID = object_id(N'%s') AND OBJECTPROPERTY(id, N'IsUserTable') = 1)\nCREATE TABLE";
 
 	/**
-	 * Create Table
+	 * DROP TABLE IF statement
 	 *
-	 * @param	string	the table name
-	 * @param	array	the fields
-	 * @param	mixed	primary key(s)
-	 * @param	mixed	key(s)
-	 * @param	bool	should 'IF NOT EXISTS' be added to the SQL
-	 * @return	string
+	 * @var	string
 	 */
-	protected function _create_table($table, $fields, $primary_keys, $keys, $if_not_exists)
-	{
-		$sql = ($if_not_exists === TRUE)
-			? "IF NOT EXISTS (SELECT * FROM sysobjects WHERE ID = object_id(N'".$table."') AND OBJECTPROPERTY(id, N'IsUserTable') = 1)\n"
-			: '';
-
-		$sql .= 'CREATE TABLE '.$this->db->escape_identifiers($table).' (';
-
-		$current_field_count = 0;
-		foreach ($fields as $field => $attributes)
-		{
-			// Numeric field names aren't allowed in databases, so if the key is
-			// numeric, we know it was assigned by PHP and the developer manually
-			// entered the field information, so we'll simply add it to the list
-			if (is_numeric($field))
-			{
-				$sql .= "\n\t".$attributes;
-			}
-			else
-			{
-				$attributes = array_change_key_case($attributes, CASE_UPPER);
-
-				$sql .= "\n\t".$this->db->escape_identifiers($field).' '.$attributes['TYPE'];
+	protected $_drop_table_if	= "IF EXISTS (SELECT * FROM sysobjects WHERE ID = object_id(N'%s') AND OBJECTPROPERTY(id, N'IsUserTable') = 1)\nDROP TABLE";
 
-				if (stripos($attributes['TYPE'], 'INT') === FALSE && ! empty($attributes['CONSTRAINT']))
-				{
-					$sql .= '('.$attributes['CONSTRAINT'].')';
-				}
-
-				if ( ! empty($attributes['UNSIGNED']) && $attributes['UNSIGNED'] === TRUE)
-				{
-					$sql .= ' UNSIGNED';
-				}
-
-				if (isset($attributes['DEFAULT']))
-				{
-					$sql .= " DEFAULT '".$attributes['DEFAULT']."'";
-				}
-
-				$sql .= ( ! empty($attributes['NULL']) && $attributes['NULL'] === TRUE)
-					? ' NULL' : ' NOT NULL';
-
-				if ( ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE)
-				{
-					$sql .= ' AUTO_INCREMENT';
-				}
-			}
+	/**
+	 * UNSIGNED support
+	 *
+	 * @var	array
+	 */
+	protected $_unsigned		= array(
+		'TINYINT'	=> 'SMALLINT',
+		'SMALLINT'	=> 'INT',
+		'INT'		=> 'BIGINT',
+		'REAL'		=> 'FLOAT'
+	);
 
-			// don't add a comma on the end of the last field
-			if (++$current_field_count < count($fields))
-			{
-				$sql .= ',';
-			}
-		}
+	// --------------------------------------------------------------------
 
-		if (count($primary_keys) > 0)
+	/**
+	 * ALTER TABLE
+	 *
+	 * @param	string	$alter_type	ALTER type
+	 * @param	string	$table		Table name
+	 * @param	mixed	$field		Column definition
+	 * @return	string|string[]
+	 */
+	protected function _alter_table($alter_type, $table, $field)
+	{
+		if (in_array($alter_type, array('ADD', 'DROP'), TRUE))
 		{
-			$sql .= ",\n\tPRIMARY KEY (".implode(', ', $this->db->escape_identifiers($primary_keys)).')';
+			return parent::_alter_table($alter_type, $table, $field);
 		}
 
-		if (is_array($keys) && count($keys) > 0)
+		$sql = 'ALTER TABLE '.$this->db->escape_identifiers($table).' ALTER COLUMN ';
+		$sqls = array();
+		for ($i = 0, $c = count($field); $i < $c; $i++)
 		{
-			foreach ($keys as $key)
-			{
-				$key = is_array($key)
-					? $this->db->escape_identifiers($key)
-					: array($this->db->escape_identifiers($key));
-
-				$sql .= ",\n\tFOREIGN KEY (".implode(', ', $key).')';
-			}
+			$sqls[] = $sql.$this->_process_column($field[$i]);
 		}
 
-		return $sql."\n)";
+		return $sqls;
 	}
 
 	// --------------------------------------------------------------------
 
 	/**
-	 * Alter table query
+	 * Field attribute TYPE
 	 *
-	 * Generates a platform-specific query so that a table can be altered
-	 * Called by add_column(), drop_column(), and column_alter(),
+	 * Performs a data type mapping between different databases.
 	 *
-	 * @param	string	the ALTER type (ADD, DROP, CHANGE)
-	 * @param	string	the column name
-	 * @param	string	the table name
-	 * @param	string	the column definition
-	 * @param	string	the default value
-	 * @param	bool	should 'NOT NULL' be added
-	 * @param	string	the field after which we should add the new field
-	 * @return	string
+	 * @param	array	&$attributes
+	 * @return	void
 	 */
-	protected function _alter_table($alter_type, $table, $column_name, $column_definition = '', $default_value = '', $null = '', $after_field = '')
+	protected function _attr_type(&$attributes)
 	{
-		$sql = 'ALTER TABLE '.$this->db->escape_identifiers($table).' '.$alter_type.' '.$this->db->escape_identifiers($column_name);
-
-		// DROP has everything it needs now.
-		if ($alter_type === 'DROP')
+		switch (strtoupper($attributes['TYPE']))
 		{
-			return $sql;
+			case 'MEDIUMINT':
+				$attributes['TYPE'] = 'INTEGER';
+				$attributes['UNSIGNED'] = FALSE;
+				return;
+			case 'INTEGER':
+				$attributes['TYPE'] = 'INT';
+				return;
+			default: return;
 		}
+	}
 
-		return $sql.' '.$column_definition
-			.($default_value != '' ? ' DEFAULT "'.$default_value.'"' : '')
-			.($null === NULL ? ' NULL' : ' NOT NULL')
-			.($after_field != '' ? ' AFTER '.$this->db->escape_identifiers($after_field) : '');
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute AUTO_INCREMENT
+	 *
+	 * @param	array	&$attributes
+	 * @param	array	&$field
+	 * @return	void
+	 */
+	protected function _attr_auto_increment(&$attributes, &$field)
+	{
+		if ( ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE && stripos($field['type'], 'int') !== FALSE)
+		{
+			$field['auto_increment'] = ' IDENTITY(1,1)';
+		}
 	}
 
 }
diff --git a/system/database/drivers/mysql/mysql_driver.php b/system/database/drivers/mysql/mysql_driver.php
index 2457e558c..b1edc2925 100644
--- a/system/database/drivers/mysql/mysql_driver.php
+++ b/system/database/drivers/mysql/mysql_driver.php
@@ -191,9 +191,21 @@ class CI_DB_mysql_driver extends CI_DB {
 	 */
 	public function version()
 	{
-		return isset($this->data_cache['version'])
-			? $this->data_cache['version']
-			: $this->data_cache['version'] = @mysql_get_server_info($this->conn_id);
+		if (isset($this->data_cache['version']))
+		{
+			return $this->data_cache['version'];
+		}
+		elseif ( ! $this->conn_id)
+		{
+			$this->initialize();
+		}
+
+		if ( ! $this->conn_id OR ($version = @mysql_get_server_info($this->conn_id)) === FALSE)
+		{
+			return FALSE;
+		}
+
+		return $this->data_cache['version'] = $version;
 	}
 
 	// --------------------------------------------------------------------
diff --git a/system/database/drivers/mysql/mysql_forge.php b/system/database/drivers/mysql/mysql_forge.php
index 7ce4e8b00..ea3207760 100644
--- a/system/database/drivers/mysql/mysql_forge.php
+++ b/system/database/drivers/mysql/mysql_forge.php
@@ -42,165 +42,140 @@ class CI_DB_mysql_forge extends CI_DB_forge {
 	 */
 	protected $_create_database	= 'CREATE DATABASE %s CHARACTER SET %s COLLATE %s';
 
-	// --------------------------------------------------------------------
-
 	/**
-	 * Process Fields
+	 * UNSIGNED support
 	 *
-	 * @param	mixed	$fields
-	 * @return	string
+	 * @var	array
 	 */
-	protected function _process_fields($fields)
-	{
-		$current_field_count = 0;
-		$sql = '';
-
-		foreach ($fields as $field => $attributes)
-		{
-			// Numeric field names aren't allowed in databases, so if the key is
-			// numeric, we know it was assigned by PHP and the developer manually
-			// entered the field information, so we'll simply add it to the list
-			if (is_numeric($field))
-			{
-				$sql .= "\n\t".$attributes;
-			}
-			else
-			{
-				$attributes = array_change_key_case($attributes, CASE_UPPER);
-
-				$sql .= "\n\t".$this->db->escape_identifiers($field);
-
-				empty($attributes['NAME']) OR $sql .= ' '.$this->db->escape_identifiers($attributes['NAME']).' ';
-
-				if ( ! empty($attributes['TYPE']))
-				{
-					$sql .=  ' '.$attributes['TYPE'];
-
-					if ( ! empty($attributes['CONSTRAINT']))
-					{
-						switch (strtolower($attributes['TYPE']))
-						{
-							case 'decimal':
-							case 'float':
-							case 'numeric':
-								$sql .= '('.implode(',', $attributes['CONSTRAINT']).')';
-								break;
-							case 'enum':
-							case 'set':
-								$sql .= '("'.implode('","', $attributes['CONSTRAINT']).'")';
-								break;
-							default:
-								$sql .= '('.$attributes['CONSTRAINT'].')';
-						}
-					}
-				}
+	protected $_unsigned		= array(
+		'TINYINT',
+		'SMALLINT',
+		'MEDIUMINT',
+		'INT',
+		'INTEGER',
+		'BIGINT',
+		'REAL',
+		'DOUBLE',
+		'DOUBLE PRECISION',
+		'FLOAT',
+		'DECIMAL',
+		'NUMERIC'
+	);
 
-				if ( ! empty($attributes['UNSIGNED']) && $attributes['UNSIGNED'] === TRUE)
-				{
-					$sql .= ' UNSIGNED';
-				}
-
-				if (isset($attributes['DEFAULT']))
-				{
-					$sql .= " DEFAULT '".$attributes['DEFAULT']."'";
-				}
-
-				$sql .= ( ! empty($attributes['NULL']) && $attributes['NULL'] === TRUE)
-					? ' NULL' : ' NOT NULL';
+	/**
+	 * NULL value representation in CREATE/ALTER TABLE statements
+	 *
+	 * @var	string
+	 */
+	protected $_null		= 'NULL';
 
-				if ( ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE)
-				{
-					$sql .= ' AUTO_INCREMENT';
-				}
-			}
+	// --------------------------------------------------------------------
 
-			// don't add a comma on the end of the last field
-			if (++$current_field_count < count($fields))
-			{
-				$sql .= ',';
-			}
-		}
+	/**
+	 * Class constructor
+	 *
+	 * @return	void
+	 */
+	public function __construct()
+	{
+		parent::__construct();
 
-		return $sql;
+		$this->_create_table .= ' DEFAULT CHARSET '.$this->db->char_set.' COLLATE '.$this->db->dbcollat;
 	}
 
 	// --------------------------------------------------------------------
 
 	/**
-	 * Create Table
+	 * ALTER TABLE
 	 *
-	 * @param	string	the table name
-	 * @param	mixed	the fields
-	 * @param	mixed	primary key(s)
-	 * @param	mixed	key(s)
-	 * @param	bool	should 'IF NOT EXISTS' be added to the SQL
-	 * @return	bool
+	 * @param	string	$alter_type	ALTER type
+	 * @param	string	$table		Table name
+	 * @param	mixed	$field		Column definition
+	 * @return	string|string[]
 	 */
-	protected function _create_table($table, $fields, $primary_keys, $keys, $if_not_exists)
+	protected function _alter_table($alter_type, $table, $field)
 	{
-		$sql = 'CREATE TABLE ';
-
-		if ($if_not_exists === TRUE)
-		{
-			$sql .= 'IF NOT EXISTS ';
-		}
-
-		$sql .= $this->db->escape_identifiers($table).' ('.$this->_process_fields($fields);
-
-		if (count($primary_keys) > 0)
+		if ($alter_type === 'DROP')
 		{
-			$key_name = $this->db->escape_identifiers(implode('_', $primary_keys));
-			$sql .= ",\n\tPRIMARY KEY ".$key_name.' ('.implode(', ', $this->db->escape_identifiers($primary_keys)).')';
+			return parent::_alter_table($alter_type, $table, $field);
 		}
 
-		if (is_array($keys) && count($keys) > 0)
+		$sql = 'ALTER TABLE '.$this->db->escape_identifiers($table);
+		for ($i = 0, $c = count($field); $i < $c; $i++)
 		{
-			foreach ($keys as $key)
+			if ($field[$i]['_literal'] !== FALSE)
 			{
-				if (is_array($key))
+				$field[$i] = ($alter_type === 'ADD')
+						? "\n\tADD ".$field[$i]['_literal']
+						: "\n\tMODIFY ".$field[$i]['_literal'];
+			}
+			else
+			{
+				if ($alter_type === 'ADD')
 				{
-					$key_name = $this->db->escape_identifiers(implode('_', $key));
-					$key = $this->db->escape_identifiers($key);
+					$field[$i]['_literal'] = "\n\tADD ";
 				}
 				else
 				{
-					$key_name = $this->db->escape_identifiers($key);
-					$key = array($key_name);
+					$field[$i]['_literal'] = empty($field['new_name']) ? "\n\tMODIFY " : "\n\tCHANGE ";
 				}
 
-				$sql .= ",\n\tKEY ".$key_name.' ('.implode(', ', $key).')';
+				$field[$i] = $field['_literal'].$this->_process_column($field[$i]);
 			}
 		}
 
-		return $sql."\n) DEFAULT CHARACTER SET ".$this->db->char_set.' COLLATE '.$this->db->dbcollat.';';
+		return array($sql.implode(',', $field));
 	}
 
 	// --------------------------------------------------------------------
 
 	/**
-	 * Alter table query
+	 * Process column
 	 *
-	 * Generates a platform-specific query so that a table can be altered
-	 * Called by add_column(), drop_column() and column_alter()
+	 * @param	array	$field
+	 * @return	string
+	 */
+	protected function _process_column($field)
+	{
+		return $this->db->escape_identifiers($field['name'])
+			.(empty($field['new_name']) ? '' : $this->db->escape_identifiers($field['new_name']))
+			.' '.$field['type'].$field['length']
+			.$field['unsigned']
+			.$field['null']
+			.$field['default']
+			.$field['auto_increment']
+			.$field['unique'];
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Process indexes
 	 *
-	 * @param	string	the ALTER type (ADD, DROP, CHANGE)
-	 * @param	string	the column name
-	 * @param	array	fields
-	 * @param	string	the field after which we should add the new field
+	 * @param	string	$table	(ignored)
 	 * @return	string
 	 */
-	protected function _alter_table($alter_type, $table, $fields, $after_field = '')
+	protected function _process_indexes($table = NULL)
 	{
-		$sql = 'ALTER TABLE '.$this->db->escape_identifiers($table).' '.$alter_type.' ';
+		$sql = '';
 
-		// DROP has everything it needs now.
-		if ($alter_type === 'DROP')
+		for ($i = 0, $c = count($this->keys); $i < $c; $i++)
 		{
-			return $sql.$this->db->escape_identifiers($fields);
+			if ( ! isset($this->fields[$this->keys[$i]]))
+			{
+				unset($this->keys[$i]);
+				continue;
+			}
+
+			is_array($this->keys[$i]) OR $this->keys[$i] = array($this->keys[$i]);
+
+			$sql .= ",\n\tKEY ".$this->db->escape_identifiers(implode('_', $this->keys[$i]))
+				.' ('.implode(', ', $this->db->escape_identifiers($this->keys[$i])).')';
 		}
 
-		return $sql.$this->_process_fields($fields)
-			.($after_field !== '' ? ' AFTER '.$this->db->escape_identifiers($after_field) : '');
+		$this->keys = array();
+
+		return $sql;
 	}
 
 }
diff --git a/system/database/drivers/mysqli/mysqli_driver.php b/system/database/drivers/mysqli/mysqli_driver.php
index 7d2507b40..ae17703ac 100644
--- a/system/database/drivers/mysqli/mysqli_driver.php
+++ b/system/database/drivers/mysqli/mysqli_driver.php
@@ -173,9 +173,16 @@ class CI_DB_mysqli_driver extends CI_DB {
 	 */
 	public function version()
 	{
-		return isset($this->data_cache['version'])
-			? $this->data_cache['version']
-			: $this->data_cache['version'] = $this->conn_id->server_info;
+		if (isset($this->data_cache['version']))
+		{
+			return $this->data_cache['version'];
+		}
+		elseif ( ! $this->conn_id)
+		{
+			$this->initialize();
+		}
+
+		return $this->data_cache['version'] = $this->conn_id->server_info;
 	}
 
 	// --------------------------------------------------------------------
diff --git a/system/database/drivers/mysqli/mysqli_forge.php b/system/database/drivers/mysqli/mysqli_forge.php
index 0732dfea5..914d6a268 100644
--- a/system/database/drivers/mysqli/mysqli_forge.php
+++ b/system/database/drivers/mysqli/mysqli_forge.php
@@ -42,165 +42,140 @@ class CI_DB_mysqli_forge extends CI_DB_forge {
 	 */
 	protected $_create_database	= 'CREATE DATABASE %s CHARACTER SET %s COLLATE %s';
 
-	// --------------------------------------------------------------------
-
 	/**
-	 * Process Fields
+	 * UNSIGNED support
 	 *
-	 * @param	mixed	$fields
-	 * @return	string
+	 * @var	array
 	 */
-	protected function _process_fields($fields)
-	{
-		$current_field_count = 0;
-		$sql = '';
-
-		foreach ($fields as $field => $attributes)
-		{
-			// Numeric field names aren't allowed in databases, so if the key is
-			// numeric, we know it was assigned by PHP and the developer manually
-			// entered the field information, so we'll simply add it to the list
-			if (is_numeric($field))
-			{
-				$sql .= "\n\t".$attributes;
-			}
-			else
-			{
-				$attributes = array_change_key_case($attributes, CASE_UPPER);
-
-				$sql .= "\n\t".$this->db->escape_identifiers($field);
-
-				empty($attributes['NAME']) OR $sql .= ' '.$this->db->escape_identifiers($attributes['NAME']).' ';
-
-				if ( ! empty($attributes['TYPE']))
-				{
-					$sql .= ' '.$attributes['TYPE'];
-
-					if ( ! empty($attributes['CONSTRAINT']))
-					{
-						switch (strtolower($attributes['TYPE']))
-						{
-							case 'decimal':
-							case 'float':
-							case 'numeric':
-								$sql .= '('.implode(',', $attributes['CONSTRAINT']).')';
-								break;
-							case 'enum':
-							case 'set':
-								$sql .= '("'.implode('","', $attributes['CONSTRAINT']).'")';
-								break;
-							default:
-								$sql .= '('.$attributes['CONSTRAINT'].')';
-						}
-					}
-				}
+	protected $_unsigned		= array(
+		'TINYINT',
+		'SMALLINT',
+		'MEDIUMINT',
+		'INT',
+		'INTEGER',
+		'BIGINT',
+		'REAL',
+		'DOUBLE',
+		'DOUBLE PRECISION',
+		'FLOAT',
+		'DECIMAL',
+		'NUMERIC'
+	);
 
-				if ( ! empty($attributes['UNSIGNED']) && $attributes['UNSIGNED'] === TRUE)
-				{
-					$sql .= ' UNSIGNED';
-				}
-
-				if (isset($attributes['DEFAULT']))
-				{
-					$sql .= " DEFAULT '".$attributes['DEFAULT']."'";
-				}
-
-				$sql .= ( ! empty($attributes['NULL']) && $attributes['NULL'] === TRUE)
-					? ' NULL' : ' NOT NULL';
+	/**
+	 * NULL value representation in CREATE/ALTER TABLE statements
+	 *
+	 * @var	string
+	 */
+	protected $_null		= 'NULL';
 
-				if ( ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE)
-				{
-					$sql .= ' AUTO_INCREMENT';
-				}
-			}
+	// --------------------------------------------------------------------
 
-			// don't add a comma on the end of the last field
-			if (++$current_field_count < count($fields))
-			{
-				$sql .= ',';
-			}
-		}
+	/**
+	 * Class constructor
+	 *
+	 * @return	void
+	 */
+	public function __construct()
+	{
+		parent::__construct();
 
-		return $sql;
+		$this->_create_table .= ' DEFAULT CHARSET '.$this->db->char_set.' COLLATE '.$this->db->dbcollat;
 	}
 
 	// --------------------------------------------------------------------
 
 	/**
-	 * Create Table
+	 * ALTER TABLE
 	 *
-	 * @param	string	the table name
-	 * @param	mixed	the fields
-	 * @param	mixed	primary key(s)
-	 * @param	mixed	key(s)
-	 * @param	bool	should 'IF NOT EXISTS' be added to the SQL
-	 * @return	bool
+	 * @param	string	$alter_type	ALTER type
+	 * @param	string	$table		Table name
+	 * @param	mixed	$field		Column definition
+	 * @return	string|string[]
 	 */
-	protected function _create_table($table, $fields, $primary_keys, $keys, $if_not_exists)
+	protected function _alter_table($alter_type, $table, $field)
 	{
-		$sql = 'CREATE TABLE ';
-
-		if ($if_not_exists === TRUE)
-		{
-			$sql .= 'IF NOT EXISTS ';
-		}
-
-		$sql .= $this->db->escape_identifiers($table).' ('.$this->_process_fields($fields);
-
-		if (count($primary_keys) > 0)
+		if ($alter_type === 'DROP')
 		{
-			$key_name = $this->db->escape_identifiers(implode('_', $primary_keys));
-			$sql .= ",\n\tPRIMARY KEY ".$key_name.' ('.implode(', ', $this->db->escape_identifiers($primary_keys)).')';
+			return parent::_alter_table($alter_type, $table, $field);
 		}
 
-		if (is_array($keys) && count($keys) > 0)
+		$sql = 'ALTER TABLE '.$this->db->escape_identifiers($table);
+		for ($i = 0, $c = count($field); $i < $c; $i++)
 		{
-			foreach ($keys as $key)
+			if ($field[$i]['_literal'] !== FALSE)
 			{
-				if (is_array($key))
+				$field[$i] = ($alter_type === 'ADD')
+						? "\n\tADD ".$field[$i]['_literal']
+						: "\n\tMODIFY ".$field[$i]['_literal'];
+			}
+			else
+			{
+				if ($alter_type === 'ADD')
 				{
-					$key_name = $this->db->escape_identifiers(implode('_', $key));
-					$key = $this->db->escape_identifiers($key);
+					$field[$i]['_literal'] = "\n\tADD ";
 				}
 				else
 				{
-					$key_name = $this->db->escape_identifiers($key);
-					$key = array($key_name);
+					$field[$i]['_literal'] = empty($field['new_name']) ? "\n\tMODIFY " : "\n\tCHANGE ";
 				}
 
-				$sql .= ",\n\tKEY ".$key_name.' ('.implode(', ', $key).')';
+				$field[$i] = $field['_literal'].$this->_process_column($field[$i]);
 			}
 		}
 
-		return $sql."\n) DEFAULT CHARACTER SET ".$this->db->char_set.' COLLATE '.$this->db->dbcollat.';';
+		return array($sql.implode(',', $field));
 	}
 
 	// --------------------------------------------------------------------
 
 	/**
-	 * Alter table query
+	 * Process column
 	 *
-	 * Generates a platform-specific query so that a table can be altered
-	 * Called by add_column(), drop_column(), and column_alter(),
+	 * @param	array	$field
+	 * @return	string
+	 */
+	protected function _process_column($field)
+	{
+		return $this->db->escape_identifiers($field['name'])
+			.(empty($field['new_name']) ? '' : $this->db->escape_identifiers($field['new_name']))
+			.' '.$field['type'].$field['length']
+			.$field['unsigned']
+			.$field['null']
+			.$field['default']
+			.$field['auto_increment']
+			.$field['unique'];
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Process indexes
 	 *
-	 * @param	string	the ALTER type (ADD, DROP, CHANGE)
-	 * @param	string	the column name
-	 * @param	array	fields
-	 * @param	string	the field after which we should add the new field
+	 * @param	string	$table	(ignored)
 	 * @return	string
 	 */
-	protected function _alter_table($alter_type, $table, $fields, $after_field = '')
+	protected function _process_indexes($table = NULL)
 	{
-		$sql = 'ALTER TABLE '.$this->db->escape_identifiers($table).' '.$alter_type.' ';
+		$sql = '';
 
-		// DROP has everything it needs now.
-		if ($alter_type === 'DROP')
+		for ($i = 0, $c = count($this->keys); $i < $c; $i++)
 		{
-			return $sql.$this->db->escape_identifiers($fields);
+			if ( ! isset($this->fields[$this->keys[$i]]))
+			{
+				unset($this->keys[$i]);
+				continue;
+			}
+
+			is_array($this->keys[$i]) OR $this->keys[$i] = array($this->keys[$i]);
+
+			$sql .= ",\n\tKEY ".$this->db->escape_identifiers(implode('_', $this->keys[$i]))
+				.' ('.implode(', ', $this->db->escape_identifiers($this->keys[$i])).')';
 		}
 
-		return $sql.$this->_process_fields($fields)
-			.($after_field !== '' ? ' AFTER '.$this->db->escape_identifiers($after_field) : '');
+		$this->keys = array();
+
+		return $sql;
 	}
 
 }
diff --git a/system/database/drivers/oci8/oci8_driver.php b/system/database/drivers/oci8/oci8_driver.php
index 38d2395b6..b2663e2c5 100644
--- a/system/database/drivers/oci8/oci8_driver.php
+++ b/system/database/drivers/oci8/oci8_driver.php
@@ -240,9 +240,21 @@ class CI_DB_oci8_driver extends CI_DB {
 	 */
 	public function version()
 	{
-		return isset($this->data_cache['version'])
-			? $this->data_cache['version']
-			: $this->data_cache['version'] = oci_server_version($this->conn_id);
+		if (isset($this->data_cache['version']))
+		{
+			return $this->data_cache['version'];
+		}
+		elseif ( ! $this->conn_id)
+		{
+			$this->initialize();
+		}
+
+		if ( ! $this->conn_id OR ($version = oci_server_version($this->conn_id)) === FALSE)
+		{
+			return FALSE;
+		}
+
+		return $this->data_cache['version'] = $version;
 	}
 
 	// --------------------------------------------------------------------
diff --git a/system/database/drivers/oci8/oci8_forge.php b/system/database/drivers/oci8/oci8_forge.php
index ad578f830..bd9d2df3c 100644
--- a/system/database/drivers/oci8/oci8_forge.php
+++ b/system/database/drivers/oci8/oci8_forge.php
@@ -50,126 +50,81 @@ class CI_DB_oci8_forge extends CI_DB_forge {
 	protected $_drop_database	= FALSE;
 
 	/**
-	 * DROP TABLE statement
+	 * DROP TABLE IF statement
 	 *
 	 * @var	string
 	 */
-	protected $_drop_table		= 'DROP TABLE %s';
+	protected $_drop_table_if	= FALSE;
+
+	/**
+	 * UNSIGNED support
+	 *
+	 * @var	bool|array
+	 */
+	protected $_unsigned		= FALSE;
 
 	// --------------------------------------------------------------------
 
 	/**
-	 * Create Table
+	 * ALTER TABLE
 	 *
-	 * @param	string	the table name
-	 * @param	array	the fields
-	 * @param	mixed	primary key(s)
-	 * @param	mixed	key(s)
-	 * @param	bool	should 'IF NOT EXISTS' be added to the SQL
-	 * @return	string
+	 * @param	string	$alter_type	ALTER type
+	 * @param	string	$table		Table name
+	 * @param	mixed	$field		Column definition
+	 * @return	string|string[]
 	 */
-	protected function _create_table($table, $fields, $primary_keys, $keys, $if_not_exists)
+	protected function _alter_table($alter_type, $table, $field)
 	{
-		$sql = 'CREATE TABLE ';
-
-		if ($if_not_exists === TRUE)
+		if ($alter_type === 'DROP')
 		{
-			$sql .= 'IF NOT EXISTS ';
+			return parent::_alter_table($alter_type, $table, $field);
+		}
+		elseif ($alter_type === 'CHANGE')
+		{
+			$alter_type = 'MODIFY';
 		}
 
-		$sql .= $this->db->escape_identifiers($table).' (';
-		$current_field_count = 0;
-
-		foreach ($fields as $field => $attributes)
+		$sql = 'ALTER TABLE '.$this->db->escape_identifiers($table);
+		$sqls = array();
+		for ($i = 0, $c = count($field); $i < $c; $i++)
 		{
-			// Numeric field names aren't allowed in databases, so if the key is
-			// numeric, we know it was assigned by PHP and the developer manually
-			// entered the field information, so we'll simply add it to the list
-			if (is_numeric($field))
+			if ($field[$i]['_literal'] !== FALSE)
 			{
-				$sql .= "\n\t".$attributes;
+				$field[$i] = "\n\t".$field[$i]['_literal'];
 			}
 			else
 			{
-				$attributes = array_change_key_case($attributes, CASE_UPPER);
-
-				$sql .= "\n\t".$this->db->escape_identifiers($field).' '.$attributes['TYPE'];
-
-				if (isset($attributes['UNSINGED']) && $attributes['UNSIGNED'] === TRUE)
-				{
-					$sql .= ' UNSIGNED';
-				}
-
-				if (isset($attributes['DEFAULT']))
+				$field[$i]['_literal'] = "\n\t".$this->_process_column($field[$i]);
+				if ($alter_type === 'MODIFY' && ! empty($field[$i]['new_name']))
 				{
-					$sql .= " DEFAULT '".$attributes['DEFAULT']."'";
+					$sqls[] = $sql.' RENAME COLUMN '.$this->db->escape_identifiers($field[$i]['name'])
+						.' '.$this->db->escape_identifiers($field[$i]['new_name']);
 				}
-
-				$sql .= (isset($attributes['NULL']) && $attributes['NULL'] === TRUE)
-					? '' : ' NOT NULL';
-
-				empty($attributes['CONSTRAINT']) OR ' CONSTRAINT '.$attributes['CONSTRAINT'];
-			}
-
-			// don't add a comma on the end of the last field
-			if (++$current_field_count < count($fields))
-			{
-				$sql .= ',';
 			}
 		}
 
-		if (count($primary_keys) > 0)
-		{
-			$sql .= ",\n\tCONSTRAINT ".$table.' PRIMARY KEY ('.implode(', ', $this->db->escape_identifiers($primary_keys)).')';
-		}
+		$sql .= ' '.$alter_type.' ';
+		$sql .= (count($field) === 1)
+				? $fields[0]
+				: '('.implode(',', $field).')';
 
-		if (is_array($keys) && count($keys) > 0)
-		{
-			foreach ($keys as $key)
-			{
-				$key = is_array($key)
-					? $this->db->escape_identifiers($key)
-					: array($this->db->escape_identifiers($key));
-
-				$sql .= ",\n\tUNIQUE COLUMNS (".implode(', ', $key).')';
-			}
-		}
-
-		return $sql."\n)";
+		// RENAME COLUMN must be executed after MODIFY
+		array_unshift($sqls, $sql);
+		return $sql;
 	}
 
 	// --------------------------------------------------------------------
 
 	/**
-	 * Alter table query
-	 *
-	 * Generates a platform-specific query so that a table can be altered
-	 * Called by add_column(), drop_column(), and column_alter(),
+	 * Field attribute AUTO_INCREMENT
 	 *
-	 * @param	string	the ALTER type (ADD, DROP, CHANGE)
-	 * @param	string	the column name
-	 * @param	string	the table name
-	 * @param	string	the column definition
-	 * @param	string	the default value
-	 * @param	bool	should 'NOT NULL' be added
-	 * @param	string	the field after which we should add the new field
-	 * @return	string
+	 * @param	array	&$attributes
+	 * @param	array	&$field
+	 * @return	void
 	 */
-	protected function _alter_table($alter_type, $table, $column_name, $column_definition = '', $default_value = '', $null = '', $after_field = '')
+	protected function _attr_auto_increment(&$attributes, &$field)
 	{
-		$sql = 'ALTER TABLE '.$this->db->escape_identifiers($table).' '.$alter_type.' '.$this->db->escape_identifiers($column_name);
-
-		// DROP has everything it needs now.
-		if ($alter_type === 'DROP')
-		{
-			return $sql;
-		}
-
-		return $sql.' '.$column_definition
-			.($default_value !== '' ? ' DEFAULT "'.$default_value.'"' : '')
-			.($null === NULL ? ' NULL' : ' NOT NULL')
-			.($after_field !== '' ? ' AFTER '.$this->db->escape_identifiers($after_field) : '');
-
+		// Not supported - sequences and triggers must be used instead
 	}
 
 }
diff --git a/system/database/drivers/odbc/odbc_forge.php b/system/database/drivers/odbc/odbc_forge.php
index 699ce996c..fb16ca5cf 100644
--- a/system/database/drivers/odbc/odbc_forge.php
+++ b/system/database/drivers/odbc/odbc_forge.php
@@ -36,130 +36,38 @@ defined('BASEPATH') OR exit('No direct script access allowed');
 class CI_DB_odbc_forge extends CI_DB_forge {
 
 	/**
-	 * DROP TABLE statement
+	 * CREATE TABLE IF statement
 	 *
 	 * @var	string
 	 */
-	protected $_drop_table		= 'DROP TABLE %s';
-
-	// --------------------------------------------------------------------
+	protected $_create_table_if	= FALSE;
 
 	/**
-	 * Create Table
+	 * DROP TABLE IF statement
 	 *
-	 * @param	string	the table name
-	 * @param	array	the fields
-	 * @param	mixed	primary key(s)
-	 * @param	mixed	key(s)
-	 * @param	bool	should 'IF NOT EXISTS' be added to the SQL
-	 * @return	bool
+	 * @var	string
 	 */
-	protected function _create_table($table, $fields, $primary_keys, $keys, $if_not_exists)
-	{
-		$sql = 'CREATE TABLE ';
-
-		if ($if_not_exists === TRUE)
-		{
-			$sql .= 'IF NOT EXISTS ';
-		}
-
-		$sql .= $this->db->escape_identifiers($table).' (';
-		$current_field_count = 0;
-
-		foreach ($fields as $field => $attributes)
-		{
-			// Numeric field names aren't allowed in databases, so if the key is
-			// numeric, we know it was assigned by PHP and the developer manually
-			// entered the field information, so we'll simply add it to the list
-			if (is_numeric($field))
-			{
-				$sql .= "\n\t".$attributes;
-			}
-			else
-			{
-				$attributes = array_change_key_case($attributes, CASE_UPPER);
-
-				$sql .= "\n\t".$this->db->escape_identifiers($field).' '.$attributes['TYPE'];
-
-				empty($attributes['CONSTRAINT']) OR $sql .= '('.$attributes['CONSTRAINT'].')';
-
-				if ( ! empty($attributes['UNSIGNED']) && $attributes['UNSIGNED'] === TRUE)
-				{
-					$sql .= ' UNSIGNED';
-				}
-
-				if (isset($attributes['DEFAULT']))
-				{
-					$sql .= " DEFAULT '".$attributes['DEFAULT']."'";
-				}
-
-				$sql .= ( ! empty($attributes['NULL']) && $attributes['NULL'] === TRUE)
-					? ' NULL' : ' NOT NULL';
+	protected $_drop_table_if	= FALSE;
 
-				if ( ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE)
-				{
-					$sql .= ' AUTO_INCREMENT';
-				}
-			}
-
-			// don't add a comma on the end of the last field
-			if (++$current_field_count < count($fields))
-			{
-				$sql .= ',';
-			}
-		}
-
-		if (count($primary_keys) > 0)
-		{
-			$sql .= ",\n\tPRIMARY KEY (".implode(', ', $this->escape_identifiers($primary_keys)).')';
-		}
-
-		if (is_array($keys) && count($keys) > 0)
-		{
-			foreach ($keys as $key)
-			{
-				$key = is_array($key)
-					? $this->db->escape_identifiers($key)
-					: array($this->db->escape_identifiers($key));
-
-				$sql .= ",\n\tFOREIGN KEY (".implode(', ', $key).')';
-			}
-		}
-
-		return $sql."\n)";
-	}
+	/**
+	 * UNSIGNED support
+	 *
+	 * @var	bool|array
+	 */
+	protected $_unsigned		= FALSE;
 
 	// --------------------------------------------------------------------
 
 	/**
-	 * Alter table query
+	 * Field attribute AUTO_INCREMENT
 	 *
-	 * Generates a platform-specific query so that a table can be altered
-	 * Called by add_column(), drop_column(), and column_alter(),
-	 *
-	 * @param	string	the ALTER type (ADD, DROP, CHANGE)
-	 * @param	string	the column name
-	 * @param	string	the table name
-	 * @param	string	the column definition
-	 * @param	string	the default value
-	 * @param	bool	should 'NOT NULL' be added
-	 * @param	string	the field after which we should add the new field
-	 * @return	string
+	 * @param	array	&$attributes
+	 * @param	array	&$field
+	 * @return	void
 	 */
-	protected function _alter_table($alter_type, $table, $column_name, $column_definition = '', $default_value = '', $null = '', $after_field = '')
+	protected function _attr_auto_increment(&$attributes, &$field)
 	{
-		$sql = 'ALTER TABLE '.$this->db->escape_identifiers($table).' '.$alter_type.' '.$this->db->escape_identifiers($column_name);
-
-		// DROP has everything it needs now.
-		if ($alter_type === 'DROP')
-		{
-			return $sql;
-		}
-
-		return $sql.' '.$column_definition
-			.($default_value != '' ? ' DEFAULT "'.$default_value.'"' : '')
-			.($null === NULL ? ' NULL' : ' NOT NULL')
-			.($after_field != '' ? ' AFTER '.$this->db->escape_identifiers($after_field) : '');
+		// Not supported (in most databases at least)
 	}
 
 }
diff --git a/system/database/drivers/pdo/pdo_driver.php b/system/database/drivers/pdo/pdo_driver.php
index 57a3c5c98..923f0e125 100644
--- a/system/database/drivers/pdo/pdo_driver.php
+++ b/system/database/drivers/pdo/pdo_driver.php
@@ -165,6 +165,10 @@ class CI_DB_pdo_driver extends CI_DB {
 		{
 			return $this->data_cache['version'];
 		}
+		elseif ( ! $this->conn_id)
+		{
+			$this->initialize();
+		}
 
 		// Not all subdrivers support the getAttribute() method
 		try
diff --git a/system/database/drivers/pdo/pdo_forge.php b/system/database/drivers/pdo/pdo_forge.php
index e77970cf2..130d3667e 100644
--- a/system/database/drivers/pdo/pdo_forge.php
+++ b/system/database/drivers/pdo/pdo_forge.php
@@ -36,139 +36,18 @@ defined('BASEPATH') OR exit('No direct script access allowed');
 class CI_DB_pdo_forge extends CI_DB_forge {
 
 	/**
-	 * DROP TABLE statement
+	 * CREATE TABLE IF statement
 	 *
 	 * @var	string
 	 */
-	protected $_drop_table		= 'DROP TABLE %s';
-
-	// --------------------------------------------------------------------
-
-	/**
-	 * Create Table
-	 *
-	 * @param	string	the table name
-	 * @param	array	the fields
-	 * @param	mixed	primary key(s)
-	 * @param	mixed	key(s)
-	 * @param	bool	should 'IF NOT EXISTS' be added to the SQL
-	 * @return	bool
-	 */
-	protected function _create_table($table, $fields, $primary_keys, $keys, $if_not_exists)
-	{
-		$sql = 'CREATE TABLE ';
-
-		if ($if_not_exists === TRUE)
-		{
-			$sql .= 'IF NOT EXISTS ';
-		}
-
-		$sql .= $this->db->escape_identifiers($table).' (';
-		$current_field_count = 0;
-
-		foreach ($fields as $field => $attributes)
-		{
-			// Numeric field names aren't allowed in databases, so if the key is
-			// numeric, we know it was assigned by PHP and the developer manually
-			// entered the field information, so we'll simply add it to the list
-			if (is_numeric($field))
-			{
-				$sql .= "\n\t".$attributes;
-			}
-			else
-			{
-				$attributes = array_change_key_case($attributes, CASE_UPPER);
-				$numeric = array('SERIAL', 'INTEGER');
-
-				$sql .= "\n\t".$this->db->escape_identifiers($field).' '.$attributes['TYPE'];
-
-				if ( ! empty($attributes['CONSTRAINT']))
-				{
-					// Exception for Postgre numeric which not too happy with constraint within those type
-					if ( ! ($this->db->subdriver === 'pgsql' && in_array($attributes['TYPE'], $numeric)))
-					{
-						$sql .= '('.$attributes['CONSTRAINT'].')';
-					}
-				}
-
-				if ( ! empty($attributes['UNSIGNED']) && $attributes['UNSIGNED'] === TRUE)
-				{
-					$sql .= ' UNSIGNED';
-				}
-
-				if (isset($attributes['DEFAULT']))
-				{
-					$sql .= " DEFAULT '".$attributes['DEFAULT']."'";
-				}
-
-				$sql .= ( ! empty($attributes['NULL']) && $attributes['NULL'] === TRUE)
-					? ' NULL' : ' NOT NULL';
-
-				if ( ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE)
-				{
-					$sql .= ' AUTO_INCREMENT';
-				}
-			}
-
-			// don't add a comma on the end of the last field
-			if (++$current_field_count < count($fields))
-			{
-				$sql .= ',';
-			}
-		}
-
-		if (count($primary_keys) > 0)
-		{
-			$sql .= ",\n\tPRIMARY KEY (".implode(', ', $this->db->escape_identifiers($primary_keys)).')';
-		}
-
-		if (is_array($keys) && count($keys) > 0)
-		{
-			foreach ($keys as $key)
-			{
-				$key = is_array($key)
-					? $this->db->escape_identifiers($key)
-					: array($this->db->escape_identifiers($key));
-
-				$sql .= ",\n\tFOREIGN KEY (".implode(', ', $key).')';
-			}
-		}
-
-		return $sql."\n)";
-	}
-
-	// --------------------------------------------------------------------
+	protected $_create_table_if	= FALSE;
 
 	/**
-	 * Alter table query
-	 *
-	 * Generates a platform-specific query so that a table can be altered
-	 * Called by add_column(), drop_column(), and column_alter(),
+	 * DROP TABLE IF statement
 	 *
-	 * @param	string	the ALTER type (ADD, DROP, CHANGE)
-	 * @param	string	the column name
-	 * @param	string	the table name
-	 * @param	string	the column definition
-	 * @param	string	the default value
-	 * @param	bool	should 'NOT NULL' be added
-	 * @param	string	the field after which we should add the new field
-	 * @return	string
+	 * @var	string
 	 */
-	protected function _alter_table($alter_type, $table, $column_name, $column_definition = '', $default_value = '', $null = '', $after_field = '')
-	{
-		$sql = 'ALTER TABLE '.$this->db->escape_identifiers($table).' '.$alter_type.' '.$this->db->escape_identifiers($column_name);
-
-		// DROP has everything it needs now.
-		if ($alter_type === 'DROP')
-		{
-			return $sql;
-		}
-
-		return $sql .' '.$column_definition
-			.($default_value !== '' ? " DEFAULT '".$default_value."'" : '')
-			.($null === NULL ? ' NULL' : ' NOT NULL')
-			.($after_field !== '' ? ' AFTER '.$this->db->escape_identifiers($after_field) : '');
-	}
+	protected $_drop_table_if	= FALSE;
 
 }
 
diff --git a/system/database/drivers/pdo/subdrivers/pdo_4d_forge.php b/system/database/drivers/pdo/subdrivers/pdo_4d_forge.php
new file mode 100644
index 000000000..231ad53a4
--- /dev/null
+++ b/system/database/drivers/pdo/subdrivers/pdo_4d_forge.php
@@ -0,0 +1,209 @@
+<?php
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP 5.2.4 or newer
+ *
+ * NOTICE OF LICENSE
+ *
+ * Licensed under the Open Software License version 3.0
+ *
+ * This source file is subject to the Open Software License (OSL 3.0) that is
+ * bundled with this package in the files license.txt / license.rst.  It is
+ * also available through the world wide web at this URL:
+ * http://opensource.org/licenses/OSL-3.0
+ * If you did not receive a copy of the license and are unable to obtain it
+ * through the world wide web, please send an email to
+ * licensing@ellislab.com so we can send you a copy immediately.
+ *
+ * @package		CodeIgniter
+ * @author		EllisLab Dev Team
+ * @copyright	Copyright (c) 2008 - 2012, EllisLab, Inc. (http://ellislab.com/)
+ * @license		http://opensource.org/licenses/OSL-3.0 Open Software License (OSL 3.0)
+ * @link		http://codeigniter.com
+ * @since		Version 2.1.0
+ * @filesource
+ */
+defined('BASEPATH') OR exit('No direct script access allowed');
+
+/**
+ * PDO 4D Forge Class
+ *
+ * @category	Database
+ * @author		EllisLab Dev Team
+ * @link		http://codeigniter.com/user_guide/database/
+ */
+class CI_DB_pdo_4d_forge extends CI_DB_4d_forge {
+
+	/**
+	 * CREATE DATABASE statement
+	 *
+	 * @var	string
+	 */
+	protected $_create_database	= 'CREATE SCHEMA %s';
+
+	/**
+	 * DROP DATABASE statement
+	 *
+	 * @var	string
+	 */
+	protected $_drop_database	= 'DROP SCHEMA %s';
+
+	/**
+	 * CREATE TABLE IF statement
+	 *
+	 * @var	string
+	 */
+	protected $_create_table_if	= 'CREATE TABLE IF NOT EXISTS';
+
+	/**
+	 * RENAME TABLE statement
+	 *
+	 * @var	string
+	 */
+	protected $_rename_table	= FALSE;
+
+	/**
+	 * DROP TABLE IF statement
+	 *
+	 * @var	string
+	 */
+	protected $_drop_table_if	= 'DROP TABLE IF EXISTS';
+
+	/**
+	 * UNSIGNED support
+	 *
+	 * @var	array
+	 */
+	protected $_unsigned		= array(
+		'INT16'		=> 'INT',
+		'SMALLINT'	=> 'INT',
+		'INT'		=> 'INT64',
+		'INT32'		=> 'INT64'
+	);
+
+	/**
+	 * DEFAULT value representation in CREATE/ALTER TABLE statements
+	 *
+	 * @var	string
+	 */
+	protected $_default		= FALSE;
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * ALTER TABLE
+	 *
+	 * @param	string	$alter_type	ALTER type
+	 * @param	string	$table		Table name
+	 * @param	mixed	$field		Column definition
+	 * @return	string|string[]
+	 */
+	protected function _alter_table($alter_type, $table, $field)
+	{
+		if (in_array($alter_type, array('ADD', 'DROP'), TRUE))
+		{
+			return parent::_alter_table($alter_table, $table, $field);
+		}
+
+		// No method of modifying columns is supported
+		return FALSE;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Process column
+	 *
+	 * @param	array	$field
+	 * @return	string
+	 */
+	protected function _process_column($field)
+	{
+		return $this->db->escape_identifiers($field['name'])
+			.' '.$field['type'].$field['length']
+			.$field['null']
+			.$field['unique']
+			.$field['auto_increment'];
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute TYPE
+	 *
+	 * Performs a data type mapping between different databases.
+	 *
+	 * @param	array	&$attributes
+	 * @return	void
+	 */
+	protected function _attr_type(&$attributes)
+	{
+		switch (strtoupper($attributes['TYPE']))
+		{
+			case 'TINYINT':
+				$attributes['TYPE'] = 'SMALLINT';
+				$attributes['UNSIGNED'] = FALSE;
+				return;
+			case 'MEDIUMINT':
+				$attributes['TYPE'] = 'INTEGER';
+				$attributes['UNSIGNED'] = FALSE;
+				return;
+			case 'INTEGER':
+				$attributes['TYPE'] = 'INT';
+				return;
+			case 'BIGINT':
+				$attribites['TYPE'] = 'INT64';
+				return;
+			default: return;
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute UNIQUE
+	 *
+	 * @param	array	&$attributes
+	 * @param	array	&$field
+	 * @return	void
+	 */
+	protected function _attr_unique(&$attributes, &$field)
+	{
+		if ( ! empty($attributes['UNIQUE']) && $attributes['UNIQUE'] === TRUE)
+		{
+			$field['unique'] = ' UNIQUE';
+
+			// UNIQUE must be used with NOT NULL
+			$field['null'] = ' NOT NULL';
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute AUTO_INCREMENT
+	 *
+	 * @param	array	&$attributes
+	 * @param	array	&$field
+	 * @return	void
+	 */
+	protected function _attr_auto_increment(&$attributes, &$field)
+	{
+		if ( ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE)
+		{
+			if (stripos($field['type'], 'int') !== FALSE)
+			{
+				$field['auto_increment'] = ' AUTO_INCREMENT';
+			}
+			elseif (strcasecmp($field['type'], 'UUID') === 0)
+			{
+				$field['auto_increment'] = ' AUTO_GENERATE';
+			}
+		}
+	}
+
+}
+
+/* End of file pdo_4d_forge.php */
+/* Location: ./system/database/drivers/pdo/subdrivers/pdo_4d_forge.php */
\ No newline at end of file
diff --git a/system/database/drivers/pdo/subdrivers/pdo_cubrid_forge.php b/system/database/drivers/pdo/subdrivers/pdo_cubrid_forge.php
new file mode 100644
index 000000000..c01a0fb81
--- /dev/null
+++ b/system/database/drivers/pdo/subdrivers/pdo_cubrid_forge.php
@@ -0,0 +1,173 @@
+<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP 5.2.4 or newer
+ *
+ * NOTICE OF LICENSE
+ *
+ * Licensed under the Open Software License version 3.0
+ *
+ * This source file is subject to the Open Software License (OSL 3.0) that is
+ * bundled with this package in the files license.txt / license.rst.  It is
+ * also available through the world wide web at this URL:
+ * http://opensource.org/licenses/OSL-3.0
+ * If you did not receive a copy of the license and are unable to obtain it
+ * through the world wide web, please send an email to
+ * licensing@ellislab.com so we can send you a copy immediately.
+ *
+ * @package		CodeIgniter
+ * @author		EllisLab Dev Team
+ * @copyright	Copyright (c) 2008 - 2012, EllisLab, Inc. (http://ellislab.com/)
+ * @license		http://opensource.org/licenses/OSL-3.0 Open Software License (OSL 3.0)
+ * @link		http://codeigniter.com
+ * @since		Version 2.1.0
+ * @filesource
+ */
+defined('BASEPATH') OR exit('No direct script access allowed');
+
+/**
+ * PDO CUBRID Forge Class
+ *
+ * @category	Database
+ * @author		EllisLab Dev Team
+ * @link		http://codeigniter.com/user_guide/database/
+ */
+class CI_DB_pdo_cubrid_forge extends CI_DB_pdo_forge {
+
+	/**
+	 * CREATE DATABASE statement
+	 *
+	 * @var	string
+	 */
+	protected $_create_database	= FALSE;
+
+	/**
+	 * DROP DATABASE statement
+	 *
+	 * @var	string
+	 */
+	protected $_drop_database	= FALSE;
+
+	/**
+	 * DROP TABLE IF statement
+	 *
+	 * @var	string
+	 */
+	protected $_drop_table_if	= 'DROP TABLE IF EXISTS';
+
+	/**
+	 * UNSIGNED support
+	 *
+	 * @var	array
+	 */
+	protected $_unsigned		= array(
+		'SHORT'		=> 'INTEGER',
+		'SMALLINT'	=> 'INTEGER',
+		'INT'		=> 'BIGINT',
+		'INTEGER'	=> 'BIGINT',
+		'BIGINT'	=> 'NUMERIC',
+		'FLOAT'		=> 'DOUBLE',
+		'REAL'		=> 'DOUBLE'
+	);
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * ALTER TABLE
+	 *
+	 * @param	string	$alter_type	ALTER type
+	 * @param	string	$table		Table name
+	 * @param	mixed	$field		Column definition
+	 * @return	string|string[]
+	 */
+	protected function _alter_table($alter_type, $table, $field)
+	{
+		if (in_array($alter_type, array('DROP', 'ADD'), TRUE))
+		{
+			return parent::_alter_table($alter_type, $table, $field);
+		}
+
+		$sql = 'ALTER TABLE '.$this->db->escape_identifiers($table);
+		$sqls = array();
+		for ($i = 0, $c = count($field); $i < $c; $i++)
+		{
+			if ($field[$i]['_literal'] !== FALSE)
+			{
+				$sqls[] = $sql.' CHANGE '.$field[$i]['_literal'];
+			}
+			else
+			{
+				$sqls[] = $sql.' CHANGE '.$this->_process_column($field[$i]);
+				if ( ! empty($field[$i]['new_name']))
+				{
+					$sqls[] = $sql.' RENAME COLUMN '.$this->db->escape_identifiers($field[$i]['name'])
+						.' AS '.$this->db->escape_identifiers($field[$i]['name']);
+				}
+			}
+		}
+
+		return $sqls;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute TYPE
+	 *
+	 * Performs a data type mapping between different databases.
+	 *
+	 * @param	array	&$attributes
+	 * @return	void
+	 */
+	protected function _attr_type(&$attributes)
+	{
+		switch (strtoupper($attributes['TYPE']))
+		{
+			case 'TINYINT':
+				$attributes['TYPE'] = 'SMALLINT';
+				$attributes['UNSIGNED'] = FALSE;
+				return;
+			case 'MEDIUMINT':
+				$attributes['TYPE'] = 'INTEGER';
+				$attributes['UNSIGNED'] = FALSE;
+				return;
+			default: return;
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Process indexes
+	 *
+	 * @param	string	$table	(ignored)
+	 * @return	string
+	 */
+	protected function _process_indexes($table = NULL)
+	{
+		$sql = '';
+
+		for ($i = 0, $c = count($this->keys); $i < $c; $i++)
+		{
+			if ( ! isset($this->fields[$this->keys[$i]]))
+			{
+				unset($this->keys[$i]);
+				continue;
+			}
+
+			is_array($this->keys[$i]) OR $this->keys[$i] = array($this->keys[$i]);
+
+			$sql .= ",\n\tKEY ".$this->db->escape_identifiers(implode('_', $this->keys[$i]))
+				.' ('.implode(', ', $this->db->escape_identifiers($this->keys[$i])).')';
+		}
+
+		$this->keys = array();
+
+		return $sql;
+	}
+
+}
+
+/* End of file pdo_cubrid_forge.php */
+/* Location: ./system/database/drivers/pdo/subdrivers/pdo_cubrid_forge.php */
\ No newline at end of file
diff --git a/system/database/drivers/pdo/subdrivers/pdo_dblib_forge.php b/system/database/drivers/pdo/subdrivers/pdo_dblib_forge.php
new file mode 100644
index 000000000..fb33127fd
--- /dev/null
+++ b/system/database/drivers/pdo/subdrivers/pdo_dblib_forge.php
@@ -0,0 +1,136 @@
+<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP 5.2.4 or newer
+ *
+ * NOTICE OF LICENSE
+ *
+ * Licensed under the Open Software License version 3.0
+ *
+ * This source file is subject to the Open Software License (OSL 3.0) that is
+ * bundled with this package in the files license.txt / license.rst.  It is
+ * also available through the world wide web at this URL:
+ * http://opensource.org/licenses/OSL-3.0
+ * If you did not receive a copy of the license and are unable to obtain it
+ * through the world wide web, please send an email to
+ * licensing@ellislab.com so we can send you a copy immediately.
+ *
+ * @package		CodeIgniter
+ * @author		EllisLab Dev Team
+ * @copyright	Copyright (c) 2008 - 2012, EllisLab, Inc. (http://ellislab.com/)
+ * @license		http://opensource.org/licenses/OSL-3.0 Open Software License (OSL 3.0)
+ * @link		http://codeigniter.com
+ * @since		Version 2.1.0
+ * @filesource
+ */
+defined('BASEPATH') OR exit('No direct script access allowed');
+
+/**
+ * PDO DBLIB Forge Class
+ *
+ * @category	Database
+ * @author		EllisLab Dev Team
+ * @link		http://codeigniter.com/user_guide/database/
+ */
+class CI_DB_pdo_dblib_forge extends CI_DB_pdo_forge {
+
+	/**
+	 * CREATE TABLE IF statement
+	 *
+	 * @var	string
+	 */
+	protected $_create_table_if	= "IF NOT EXISTS (SELECT * FROM sysobjects WHERE ID = object_id(N'%s') AND OBJECTPROPERTY(id, N'IsUserTable') = 1)\nCREATE TABLE";
+
+	/**
+	 * DROP TABLE IF statement
+	 *
+	 * @var	string
+	 */
+	protected $_drop_table_if	= "IF EXISTS (SELECT * FROM sysobjects WHERE ID = object_id(N'%s') AND OBJECTPROPERTY(id, N'IsUserTable') = 1)\nDROP TABLE";
+
+	/**
+	 * UNSIGNED support
+	 *
+	 * @var	array
+	 */
+	protected $_unsigned		= array(
+		'TINYINT'	=> 'SMALLINT',
+		'SMALLINT'	=> 'INT',
+		'INT'		=> 'BIGINT',
+		'REAL'		=> 'FLOAT'
+	);
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * ALTER TABLE
+	 *
+	 * @param	string	$alter_type	ALTER type
+	 * @param	string	$table		Table name
+	 * @param	mixed	$field		Column definition
+	 * @return	string|string[]
+	 */
+	protected function _alter_table($alter_type, $table, $field)
+	{
+		if (in_array($alter_type, array('ADD', 'DROP'), TRUE))
+		{
+			return parent::_alter_table($alter_type, $table, $field);
+		}
+
+		$sql = 'ALTER TABLE '.$this->db->escape_identifiers($table).' ALTER COLUMN ';
+		$sqls = array();
+		for ($i = 0, $c = count($field); $i < $c; $i++)
+		{
+			$sqls[] = $sql.$this->_process_column($field[$i]);
+		}
+
+		return $sqls;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute TYPE
+	 *
+	 * Performs a data type mapping between different databases.
+	 *
+	 * @param	array	&$attributes
+	 * @return	void
+	 */
+	protected function _attr_type(&$attributes)
+	{
+		switch (strtoupper($attributes['TYPE']))
+		{
+			case 'MEDIUMINT':
+				$attributes['TYPE'] = 'INTEGER';
+				$attributes['UNSIGNED'] = FALSE;
+				return;
+			case 'INTEGER':
+				$attributes['TYPE'] = 'INT';
+				return;
+			default: return;
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute AUTO_INCREMENT
+	 *
+	 * @param	array	&$attributes
+	 * @param	array	&$field
+	 * @return	void
+	 */
+	protected function _attr_auto_increment(&$attributes, &$field)
+	{
+		if ( ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE && stripos($field['type'], 'int') !== FALSE)
+		{
+			$field['auto_increment'] = ' IDENTITY(1,1)';
+		}
+	}
+
+}
+
+/* End of file pdo_dblib_forge.php */
+/* Location: ./system/database/drivers/pdo/subdrivers/pdo_dblib_forge.php */
\ No newline at end of file
diff --git a/system/database/drivers/pdo/subdrivers/pdo_firebird_forge.php b/system/database/drivers/pdo/subdrivers/pdo_firebird_forge.php
new file mode 100644
index 000000000..88c53510a
--- /dev/null
+++ b/system/database/drivers/pdo/subdrivers/pdo_firebird_forge.php
@@ -0,0 +1,228 @@
+<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP 5.2.4 or newer
+ *
+ * NOTICE OF LICENSE
+ *
+ * Licensed under the Open Software License version 3.0
+ *
+ * This source file is subject to the Open Software License (OSL 3.0) that is
+ * bundled with this package in the files license.txt / license.rst.  It is
+ * also available through the world wide web at this URL:
+ * http://opensource.org/licenses/OSL-3.0
+ * If you did not receive a copy of the license and are unable to obtain it
+ * through the world wide web, please send an email to
+ * licensing@ellislab.com so we can send you a copy immediately.
+ *
+ * @package		CodeIgniter
+ * @author		EllisLab Dev Team
+ * @copyright	Copyright (c) 2008 - 2012, EllisLab, Inc. (http://ellislab.com/)
+ * @license		http://opensource.org/licenses/OSL-3.0 Open Software License (OSL 3.0)
+ * @link		http://codeigniter.com
+ * @since		Version 2.1.0
+ * @filesource
+ */
+defined('BASEPATH') OR exit('No direct script access allowed');
+
+/**
+ * PDO Firebird Forge Class
+ *
+ * @category	Database
+ * @author		EllisLab Dev Team
+ * @link		http://codeigniter.com/user_guide/database/
+ */
+class CI_DB_pdo_firebird_forge extends CI_DB_pdo_forge {
+
+	/**
+	 * RENAME TABLE statement
+	 *
+	 * @var	string
+	 */
+	protected $_rename_table	= FALSE;
+
+	/**
+	 * UNSIGNED support
+	 *
+	 * @var	array
+	 */
+	protected $_unsigned		= array(
+		'SMALLINT'	=> 'INTEGER',
+		'INTEGER'	=> 'INT64',
+		'FLOAT'		=> 'DOUBLE PRECISION'
+	);
+
+	/**
+	 * NULL value representation in CREATE/ALTER TABLE statements
+	 *
+	 * @var	string
+	 */
+	protected $_null		= 'NULL';
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Create database
+	 *
+	 * @param	string	$db_name
+	 * @return	string
+	 */
+	public function create_database($db_name)
+	{
+		// Firebird databases are flat files, so a path is required
+
+		// Hostname is needed for remote access
+		empty($this->db->hostname) OR $db_name = $this->hostname.':'.$db_name;
+
+		return parent::create_database('"'.$db_name.'"');
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Drop database
+	 *
+	 * @param	string	$db_name	(ignored)
+	 * @return	bool
+	 */
+	public function drop_database($db_name = '')
+	{
+		if ( ! ibase_drop_db($this->conn_id))
+		{
+			return ($this->db->db_debug) ? $this->db->display_error('db_unable_to_drop') : FALSE;
+		}
+		elseif ( ! empty($this->db->data_cache['db_names']))
+		{
+			$key = array_search(strtolower($this->db->database), array_map('strtolower', $this->db->data_cache['db_names']), TRUE);
+			if ($key !== FALSE)
+			{
+				unset($this->db->data_cache['db_names'][$key]);
+			}
+		}
+
+		return TRUE;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * ALTER TABLE
+	 *
+	 * @param	string	$alter_type	ALTER type
+	 * @param	string	$table		Table name
+	 * @param	mixed	$field		Column definition
+	 * @return	string|string[]
+	 */
+	protected function _alter_table($alter_type, $table, $field)
+ 	{
+		if (in_array($alter_type, array('DROP', 'ADD'), TRUE))
+		{
+			return parent::_alter_table($alter_type, $table, $field);
+		}
+
+		$sql = 'ALTER TABLE '.$this->db->escape_identifiers($table);
+		$sqls = array();
+		for ($i = 0, $c = count($field), $sql .= $alter_type.' '; $i < $c; $i++)
+		{
+			if ($field[$i]['_literal'] !== FALSE)
+			{
+				return FALSE;
+			}
+
+			if (isset($field[$i]['type']))
+			{
+				$sqls[] = $sql.' TYPE '.$field[$i]['type'].$field[$i]['length'];
+			}
+
+			if ( ! empty($field[$i]['default']))
+			{
+				$sqls[] = $sql.' ALTER '.$this->db->escape_identifiers($field[$i]['name'])
+					.' SET '.$field[$i]['default'];
+			}
+
+			if (isset($field[$i]['null']))
+			{
+				$sqls[] = 'UPDATE "RDB$RELATION_FIELDS" SET "RDB$NULL_FLAG" = '
+					.($field[$i]['null'] === TRUE ? 'NULL' : '1')
+					.' WHERE "RDB$FIELD_NAME" = '.$this->db->escape($field[$i]['name'])
+					.' AND "RDB$RELATION_NAME" = '.$this->db->escape($table);
+			}
+
+			if ( ! empty($field[$i]['new_name']))
+			{
+				$sqls[] = $sql.' ALTER '.$this->db->escape_identifiers($field[$i]['name'])
+					.' TO '.$this->db->escape_identifiers($field[$i]['new_name']);
+			}
+		}
+
+		return $sqls;
+ 	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Process column
+	 *
+	 * @param	array	$field
+	 * @return	string
+	 */
+	protected function _process_column($field)
+	{
+		return $this->db->escape_identifiers($field['name'])
+			.' '.$field['type'].$field['length']
+			.$field['null']
+			.$field['unique']
+			.$field['default'];
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute TYPE
+	 *
+	 * Performs a data type mapping between different databases.
+	 *
+	 * @param	array	&$attributes
+	 * @return	void
+	 */
+	protected function _attr_type(&$attributes)
+	{
+		switch (strtoupper($attributes['TYPE']))
+		{
+			case 'TINYINT':
+				$attributes['TYPE'] = 'SMALLINT';
+				$attributes['UNSIGNED'] = FALSE;
+				return;
+			case 'MEDIUMINT':
+				$attributes['TYPE'] = 'INTEGER';
+				$attributes['UNSIGNED'] = FALSE;
+				return;
+			case 'INT':
+				$attributes['TYPE'] = 'INTEGER';
+				return;
+			case 'BIGINT':
+				$attributes['TYPE'] = 'INT64';
+				return;
+			default: return;
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute AUTO_INCREMENT
+	 *
+	 * @param	array	&$attributes
+	 * @param	array	&$field
+	 * @return	void
+	 */
+	protected function _attr_auto_increment(&$attributes, &$field)
+	{
+		// Not supported
+	}
+
+}
+
+/* End of file pdo_firebird_forge.php */
+/* Location: ./system/database/drivers/pdo/subdrivers/pdo_firebird_forge.php */
\ No newline at end of file
diff --git a/system/database/drivers/pdo/subdrivers/pdo_ibm_forge.php b/system/database/drivers/pdo/subdrivers/pdo_ibm_forge.php
new file mode 100644
index 000000000..6a2c9b87e
--- /dev/null
+++ b/system/database/drivers/pdo/subdrivers/pdo_ibm_forge.php
@@ -0,0 +1,146 @@
+<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP 5.2.4 or newer
+ *
+ * NOTICE OF LICENSE
+ *
+ * Licensed under the Open Software License version 3.0
+ *
+ * This source file is subject to the Open Software License (OSL 3.0) that is
+ * bundled with this package in the files license.txt / license.rst.  It is
+ * also available through the world wide web at this URL:
+ * http://opensource.org/licenses/OSL-3.0
+ * If you did not receive a copy of the license and are unable to obtain it
+ * through the world wide web, please send an email to
+ * licensing@ellislab.com so we can send you a copy immediately.
+ *
+ * @package		CodeIgniter
+ * @author		EllisLab Dev Team
+ * @copyright	Copyright (c) 2008 - 2012, EllisLab, Inc. (http://ellislab.com/)
+ * @license		http://opensource.org/licenses/OSL-3.0 Open Software License (OSL 3.0)
+ * @link		http://codeigniter.com
+ * @since		Version 2.1.0
+ * @filesource
+ */
+defined('BASEPATH') OR exit('No direct script access allowed');
+
+/**
+ * PDO IBM DB2 Forge Class
+ *
+ * @category	Database
+ * @author		EllisLab Dev Team
+ * @link		http://codeigniter.com/user_guide/database/
+ */
+class CI_DB_pdo_ibm_forge extends CI_DB_pdo_forge {
+
+	/**
+	 * RENAME TABLE IF statement
+	 *
+	 * @var	string
+	 */
+	protected $_rename_table	= 'RENAME TABLE %s TO %s';
+
+	/**
+	 * UNSIGNED support
+	 *
+	 * @var	array
+	 */
+	protected $_unsigned		= array(
+		'SMALLINT'	=> 'INTEGER',
+		'INT'		=> 'BIGINT',
+		'INTEGER'	=> 'BIGINT'
+	);
+
+	/**
+	 * DEFAULT value representation in CREATE/ALTER TABLE statements
+	 *
+	 * @var	string
+	 */
+	protected $_default		= FALSE;
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * ALTER TABLE
+	 *
+	 * @param	string	$alter_type	ALTER type
+	 * @param	string	$table		Table name
+	 * @param	mixed	$field		Column definition
+	 * @return	string|string[]
+	 */
+	protected function _alter_table($alter_type, $table, $field)
+	{
+		if ($alter_type === 'CHANGE')
+		{
+			$alter_type = 'MODIFY';
+		}
+
+		return parent::_alter_table($alter_type, $table, $field);
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute TYPE
+	 *
+	 * Performs a data type mapping between different databases.
+	 *
+	 * @param	array	&$attributes
+	 * @return	void
+	 */
+	protected function _attr_type(&$attributes)
+	{
+		switch (strtoupper($attributes['TYPE']))
+		{
+			case 'TINYINT':
+				$attributes['TYPE'] = 'SMALLINT';
+				$attributes['UNSIGNED'] = FALSE;
+				return;
+			case 'MEDIUMINT':
+				$attributes['TYPE'] = 'INTEGER';
+				$attributes['UNSIGNED'] = FALSE;
+				return;
+			default: return;
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute UNIQUE
+	 *
+	 * @param	array	&$attributes
+	 * @param	array	&$field
+	 * @return	void
+	 */
+	protected function _attr_unique(&$attributes, &$field)
+	{
+		if ( ! empty($attributes['UNIQUE']) && $attributes['UNIQUE'] === TRUE)
+		{
+			$field['unique'] = ' UNIQUE';
+
+			// UNIQUE must be used with NOT NULL
+			$field['null'] = ' NOT NULL';
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute AUTO_INCREMENT
+	 *
+	 * @param	array	&$attributes
+	 * @param	array	&$field
+	 * @return	void
+	 */
+	protected function _attr_auto_increment(&$attributes, &$field)
+	{
+		// Not supported
+	}
+
+}
+
+/* End of file pdo_ibm_forge.php */
+/* Location: ./system/database/drivers/pdo/subdrivers/pdo_ibm_forge.php */
\ No newline at end of file
diff --git a/system/database/drivers/pdo/subdrivers/pdo_informix_forge.php b/system/database/drivers/pdo/subdrivers/pdo_informix_forge.php
new file mode 100644
index 000000000..715a7cbba
--- /dev/null
+++ b/system/database/drivers/pdo/subdrivers/pdo_informix_forge.php
@@ -0,0 +1,155 @@
+<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP 5.2.4 or newer
+ *
+ * NOTICE OF LICENSE
+ *
+ * Licensed under the Open Software License version 3.0
+ *
+ * This source file is subject to the Open Software License (OSL 3.0) that is
+ * bundled with this package in the files license.txt / license.rst.  It is
+ * also available through the world wide web at this URL:
+ * http://opensource.org/licenses/OSL-3.0
+ * If you did not receive a copy of the license and are unable to obtain it
+ * through the world wide web, please send an email to
+ * licensing@ellislab.com so we can send you a copy immediately.
+ *
+ * @package		CodeIgniter
+ * @author		EllisLab Dev Team
+ * @copyright	Copyright (c) 2008 - 2012, EllisLab, Inc. (http://ellislab.com/)
+ * @license		http://opensource.org/licenses/OSL-3.0 Open Software License (OSL 3.0)
+ * @link		http://codeigniter.com
+ * @since		Version 2.1.0
+ * @filesource
+ */
+defined('BASEPATH') OR exit('No direct script access allowed');
+
+/**
+ * PDO Informix Forge Class
+ *
+ * @category	Database
+ * @author		EllisLab Dev Team
+ * @link		http://codeigniter.com/user_guide/database/
+ */
+class CI_DB_pdo_informix_forge extends CI_DB_pdo_forge {
+
+	/**
+	 * RENAME TABLE statement
+	 *
+	 * @var	string
+	 */
+	protected $_rename_table	= 'RENAME TABLE %s TO %s';
+
+	/**
+	 * UNSIGNED support
+	 *
+	 * @var	array
+	 */
+	protected $_unsigned		= array(
+		'SMALLINT'	=> 'INTEGER',
+		'INT'		=> 'BIGINT',
+		'INTEGER'	=> 'BIGINT',
+		'REAL'		=> 'DOUBLE PRECISION',
+		'SMALLFLOAT'	=> 'DOUBLE PRECISION'
+	);
+
+	/**
+	 * DEFAULT value representation in CREATE/ALTER TABLE statements
+	 *
+	 * @var	string
+	 */
+	protected $_default		= ', ';
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * ALTER TABLE
+	 *
+	 * @param	string	$alter_type	ALTER type
+	 * @param	string	$table		Table name
+	 * @param	mixed	$field		Column definition
+	 * @return	string|string[]
+	 */
+	protected function _alter_table($alter_type, $table, $field)
+	{
+		if ($alter_type === 'CHANGE')
+		{
+			$alter_type = 'MODIFY';
+		}
+
+		return parent::_alter_table($alter_type, $table, $field);
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute TYPE
+	 *
+	 * Performs a data type mapping between different databases.
+	 *
+	 * @param	array	&$attributes
+	 * @return	void
+	 */
+	protected function _attr_type(&$attributes)
+	{
+		switch (strtoupper($attributes['TYPE']))
+		{
+			case 'TINYINT':
+				$attributes['TYPE'] = 'SMALLINT';
+				$attributes['UNSIGNED'] = FALSE;
+				return;
+			case 'MEDIUMINT':
+				$attributes['TYPE'] = 'INTEGER';
+				$attributes['UNSIGNED'] = FALSE;
+				return;
+			case 'BYTE':
+			case 'TEXT':
+			case 'BLOB':
+			case 'CLOB':
+				$attributes['UNIQUE'] = FALSE;
+				if (isset($attributes['DEFAULT']))
+				{
+					unset($attributes['DEFAULT']);
+				}
+				return;
+			default: return;
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute UNIQUE
+	 *
+	 * @param	array	&$attributes
+	 * @param	array	&$field
+	 * @return	void
+	 */
+	protected function _attr_unique(&$attributes, &$field)
+	{
+		if ( ! empty($attributes['UNIQUE']) && $attributes['UNIQUE'] === TRUE)
+		{
+			$field['unique'] = ' UNIQUE CONSTRAINT '.$this->db->escape_identifiers($field['name']);
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute AUTO_INCREMENT
+	 *
+	 * @param	array	&$attributes
+	 * @param	array	&$field
+	 * @return	void
+	 */
+	protected function _attr_auto_increment(&$attributes, &$field)
+	{
+		// Not supported
+	}
+
+}
+
+/* End of file pdo_informix_forge.php */
+/* Location: ./system/database/drivers/pdo/subdrivers/pdo_informix_forge.php */
\ No newline at end of file
diff --git a/system/database/drivers/pdo/subdrivers/pdo_mysql_forge.php b/system/database/drivers/pdo/subdrivers/pdo_mysql_forge.php
new file mode 100644
index 000000000..dc856ed2c
--- /dev/null
+++ b/system/database/drivers/pdo/subdrivers/pdo_mysql_forge.php
@@ -0,0 +1,198 @@
+<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP 5.2.4 or newer
+ *
+ * NOTICE OF LICENSE
+ *
+ * Licensed under the Open Software License version 3.0
+ *
+ * This source file is subject to the Open Software License (OSL 3.0) that is
+ * bundled with this package in the files license.txt / license.rst.  It is
+ * also available through the world wide web at this URL:
+ * http://opensource.org/licenses/OSL-3.0
+ * If you did not receive a copy of the license and are unable to obtain it
+ * through the world wide web, please send an email to
+ * licensing@ellislab.com so we can send you a copy immediately.
+ *
+ * @package		CodeIgniter
+ * @author		EllisLab Dev Team
+ * @copyright	Copyright (c) 2008 - 2012, EllisLab, Inc. (http://ellislab.com/)
+ * @license		http://opensource.org/licenses/OSL-3.0 Open Software License (OSL 3.0)
+ * @link		http://codeigniter.com
+ * @since		Version 2.1.0
+ * @filesource
+ */
+defined('BASEPATH') OR exit('No direct script access allowed');
+
+/**
+ * PDO MySQL Forge Class
+ *
+ * @category	Database
+ * @author		EllisLab Dev Team
+ * @link		http://codeigniter.com/user_guide/database/
+ */
+class CI_DB_pdo_mysql_forge extends CI_DB_pdo_forge {
+
+	/**
+	 * CREATE DATABASE statement
+	 *
+	 * @var	string
+	 */
+	protected $_create_database	= 'CREATE DATABASE %s CHARACTER SET %s COLLATE %s';
+
+	/**
+	 * CREATE TABLE IF statement
+	 *
+	 * @var	string
+	 */
+	protected $_create_table_if	= 'CREATE TABLE IF NOT EXISTS';
+
+	/**
+	 * DROP TABLE IF statement
+	 *
+	 * @var	string
+	 */
+	protected $_drop_table_if	= 'DROP TABLE IF EXISTS';
+
+	/**
+	 * UNSIGNED support
+	 *
+	 * @var	array
+	 */
+	protected $_unsigned		= array(
+		'TINYINT',
+		'SMALLINT',
+		'MEDIUMINT',
+		'INT',
+		'INTEGER',
+		'BIGINT',
+		'REAL',
+		'DOUBLE',
+		'DOUBLE PRECISION',
+		'FLOAT',
+		'DECIMAL',
+		'NUMERIC'
+	);
+
+	/**
+	 * NULL value representation in CREATE/ALTER TABLE statements
+	 *
+	 * @var	string
+	 */
+	protected $_null		= 'NULL';
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Class constructor
+	 *
+	 * @return	void
+	 */
+	public function __construct()
+	{
+		parent::__construct();
+
+		$this->_create_table .= ' DEFAULT CHARSET '.$this->db->char_set.' COLLATE '.$this->db->dbcollat;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * ALTER TABLE
+	 *
+	 * @param	string	$alter_type	ALTER type
+	 * @param	string	$table		Table name
+	 * @param	mixed	$field		Column definition
+	 * @return	string|string[]
+	 */
+	protected function _alter_table($alter_type, $table, $field)
+	{
+		if ($alter_type === 'DROP')
+		{
+			return parent::_alter_table($alter_type, $table, $field);
+		}
+
+		$sql = 'ALTER TABLE '.$this->db->escape_identifiers($table);
+		for ($i = 0, $c = count($field); $i < $c; $i++)
+		{
+			if ($field[$i]['_literal'] !== FALSE)
+			{
+				$field[$i] = ($alter_type === 'ADD')
+						? "\n\tADD ".$field[$i]['_literal']
+						: "\n\tMODIFY ".$field[$i]['_literal'];
+			}
+			else
+			{
+				if ($alter_type === 'ADD')
+				{
+					$field[$i]['_literal'] = "\n\tADD ";
+				}
+				else
+				{
+					$field[$i]['_literal'] = empty($field['new_name']) ? "\n\tMODIFY " : "\n\tCHANGE ";
+				}
+
+				$field[$i] = $field['_literal'].$this->_process_column($field[$i]);
+			}
+		}
+
+		return array($sql.implode(',', $field));
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Process column
+	 *
+	 * @param	array	$field
+	 * @return	string
+	 */
+	protected function _process_column($field)
+	{
+		return $this->db->escape_identifiers($field['name'])
+			.(empty($field['new_name']) ? '' : $this->db->escape_identifiers($field['new_name']))
+			.' '.$field['type'].$field['length']
+			.$field['unsigned']
+			.$field['null']
+			.$field['default']
+			.$field['auto_increment']
+			.$field['unique'];
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Process indexes
+	 *
+	 * @param	string	$table	(ignored)
+	 * @return	string
+	 */
+	protected function _process_indexes($table = NULL)
+	{
+		$sql = '';
+
+		for ($i = 0, $c = count($this->keys); $i < $c; $i++)
+		{
+			if ( ! isset($this->fields[$this->keys[$i]]))
+			{
+				unset($this->keys[$i]);
+				continue;
+			}
+
+			is_array($this->keys[$i]) OR $this->keys[$i] = array($this->keys[$i]);
+
+			$sql .= ",\n\tKEY ".$this->db->escape_identifiers(implode('_', $this->keys[$i]))
+				.' ('.implode(', ', $this->db->escape_identifiers($this->keys[$i])).')';
+		}
+
+		$this->keys = array();
+
+		return $sql;
+	}
+
+}
+
+/* End of file pdo_mysql_forge.php */
+/* Location: ./system/database/drivers/pdo/subdrivers/pdo_mysql_forge.php */
\ No newline at end of file
diff --git a/system/database/drivers/pdo/subdrivers/pdo_oci_forge.php b/system/database/drivers/pdo/subdrivers/pdo_oci_forge.php
new file mode 100644
index 000000000..dbcb64d31
--- /dev/null
+++ b/system/database/drivers/pdo/subdrivers/pdo_oci_forge.php
@@ -0,0 +1,133 @@
+<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP 5.2.4 or newer
+ *
+ * NOTICE OF LICENSE
+ *
+ * Licensed under the Open Software License version 3.0
+ *
+ * This source file is subject to the Open Software License (OSL 3.0) that is
+ * bundled with this package in the files license.txt / license.rst.  It is
+ * also available through the world wide web at this URL:
+ * http://opensource.org/licenses/OSL-3.0
+ * If you did not receive a copy of the license and are unable to obtain it
+ * through the world wide web, please send an email to
+ * licensing@ellislab.com so we can send you a copy immediately.
+ *
+ * @package		CodeIgniter
+ * @author		EllisLab Dev Team
+ * @copyright	Copyright (c) 2008 - 2012, EllisLab, Inc. (http://ellislab.com/)
+ * @license		http://opensource.org/licenses/OSL-3.0 Open Software License (OSL 3.0)
+ * @link		http://codeigniter.com
+ * @since		Version 2.1.0
+ * @filesource
+ */
+defined('BASEPATH') OR exit('No direct script access allowed');
+
+/**
+ * PDO Oracle Forge Class
+ *
+ * @category	Database
+ * @author		EllisLab Dev Team
+ * @link		http://codeigniter.com/user_guide/database/
+ */
+class CI_DB_pdo_oci_forge extends CI_DB_pdo_forge {
+
+	/**
+	 * CREATE DATABASE statement
+	 *
+	 * @var	string
+	 */
+	protected $_create_database	= FALSE;
+
+	/**
+	 * DROP DATABASE statement
+	 *
+	 * @var	string
+	 */
+	protected $_drop_database	= FALSE;
+
+	/**
+	 * CREATE TABLE IF statement
+	 *
+	 * @var	string
+	 */
+	protected $_create_table_if	= 'CREATE TABLE IF NOT EXISTS';
+
+	/**
+	 * UNSIGNED support
+	 *
+	 * @var	bool|array
+	 */
+	protected $_unsigned		= FALSE;
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * ALTER TABLE
+	 *
+	 * @param	string	$alter_type	ALTER type
+	 * @param	string	$table		Table name
+	 * @param	mixed	$field		Column definition
+	 * @return	string|string[]
+	 */
+	protected function _alter_table($alter_type, $table, $field)
+	{
+		if ($alter_type === 'DROP')
+		{
+			return parent::_alter_table($alter_type, $table, $field);
+		}
+		elseif ($alter_type === 'CHANGE')
+		{
+			$alter_type = 'MODIFY';
+		}
+
+		$sql = 'ALTER TABLE '.$this->db->escape_identifiers($table);
+		$sqls = array();
+		for ($i = 0, $c = count($field); $i < $c; $i++)
+		{
+			if ($field[$i]['_literal'] !== FALSE)
+			{
+				$field[$i] = "\n\t".$field[$i]['_literal'];
+			}
+			else
+			{
+				$field[$i]['_literal'] = "\n\t".$this->_process_column($field[$i]);
+				if ($alter_type === 'MODIFY' && ! empty($field[$i]['new_name']))
+				{
+					$sqls[] = $sql.' RENAME COLUMN '.$this->db->escape_identifiers($field[$i]['name'])
+						.' '.$this->db->escape_identifiers($field[$i]['new_name']);
+				}
+			}
+		}
+
+		$sql .= ' '.$alter_type.' ';
+		$sql .= (count($field) === 1)
+				? $fields[0]
+				: '('.implode(',', $field).')';
+
+		// RENAME COLUMN must be executed after MODIFY
+		array_unshift($sqls, $sql);
+		return $sql;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute AUTO_INCREMENT
+	 *
+	 * @param	array	&$attributes
+	 * @param	array	&$field
+	 * @return	void
+	 */
+	protected function _attr_auto_increment(&$attributes, &$field)
+	{
+		// Not supported - sequences and triggers must be used instead
+	}
+
+}
+
+/* End of file pdo_oci_forge.php */
+/* Location: ./system/database/drivers/pdo/subdrivers/pdo_oci_forge.php */
\ No newline at end of file
diff --git a/system/database/drivers/pdo/subdrivers/pdo_odbc_forge.php b/system/database/drivers/pdo/subdrivers/pdo_odbc_forge.php
new file mode 100644
index 000000000..cd6b19c68
--- /dev/null
+++ b/system/database/drivers/pdo/subdrivers/pdo_odbc_forge.php
@@ -0,0 +1,62 @@
+<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP 5.2.4 or newer
+ *
+ * NOTICE OF LICENSE
+ *
+ * Licensed under the Open Software License version 3.0
+ *
+ * This source file is subject to the Open Software License (OSL 3.0) that is
+ * bundled with this package in the files license.txt / license.rst.  It is
+ * also available through the world wide web at this URL:
+ * http://opensource.org/licenses/OSL-3.0
+ * If you did not receive a copy of the license and are unable to obtain it
+ * through the world wide web, please send an email to
+ * licensing@ellislab.com so we can send you a copy immediately.
+ *
+ * @package		CodeIgniter
+ * @author		EllisLab Dev Team
+ * @copyright	Copyright (c) 2008 - 2012, EllisLab, Inc. (http://ellislab.com/)
+ * @license		http://opensource.org/licenses/OSL-3.0 Open Software License (OSL 3.0)
+ * @link		http://codeigniter.com
+ * @since		Version 2.1.0
+ * @filesource
+ */
+defined('BASEPATH') OR exit('No direct script access allowed');
+
+/**
+ * PDO ODBC Forge Class
+ *
+ * @category	Database
+ * @author		EllisLab Dev Team
+ * @link		http://codeigniter.com/database/
+ */
+class CI_DB_pdo_odbc_forge extends CI_DB_pdo_forge {
+
+	/**
+	 * UNSIGNED support
+	 *
+	 * @var	bool|array
+	 */
+	protected $_unsigned		= FALSE;
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute AUTO_INCREMENT
+	 *
+	 * @param	array	&$attributes
+	 * @param	array	&$field
+	 * @return	void
+	 */
+	protected function _attr_auto_increment(&$attributes, &$field)
+	{
+		// Not supported (in most databases at least)
+	}
+
+}
+
+/* End of file pdo_odbc_forge.php */
+/* Location: ./system/database/drivers/pdo/subdrivers/pdo_odbc_forge.php */
\ No newline at end of file
diff --git a/system/database/drivers/pdo/subdrivers/pdo_pgsql_forge.php b/system/database/drivers/pdo/subdrivers/pdo_pgsql_forge.php
new file mode 100644
index 000000000..b5235d24b
--- /dev/null
+++ b/system/database/drivers/pdo/subdrivers/pdo_pgsql_forge.php
@@ -0,0 +1,193 @@
+<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP 5.2.4 or newer
+ *
+ * NOTICE OF LICENSE
+ *
+ * Licensed under the Open Software License version 3.0
+ *
+ * This source file is subject to the Open Software License (OSL 3.0) that is
+ * bundled with this package in the files license.txt / license.rst.  It is
+ * also available through the world wide web at this URL:
+ * http://opensource.org/licenses/OSL-3.0
+ * If you did not receive a copy of the license and are unable to obtain it
+ * through the world wide web, please send an email to
+ * licensing@ellislab.com so we can send you a copy immediately.
+ *
+ * @package		CodeIgniter
+ * @author		EllisLab Dev Team
+ * @copyright	Copyright (c) 2008 - 2012, EllisLab, Inc. (http://ellislab.com/)
+ * @license		http://opensource.org/licenses/OSL-3.0 Open Software License (OSL 3.0)
+ * @link		http://codeigniter.com
+ * @since		Version 2.1.0
+ * @filesource
+ */
+defined('BASEPATH') OR exit('No direct script access allowed');
+
+/**
+ * PDO PostgreSQL Forge Class
+ *
+ * @category	Database
+ * @author		EllisLab Dev Team
+ * @link		http://codeigniter.com/user_guide/database/
+ */
+class CI_DB_pdo_pgsql_forge extends CI_DB_pdo_forge {
+
+	/**
+	 * DROP TABLE IF statement
+	 *
+	 * @var	string
+	 */
+	protected $_drop_table_if	= 'DROP TABLE IF EXISTS';
+
+	/**
+	 * UNSIGNED support
+	 *
+	 * @var	array
+	 */
+	protected $_unsigned		= array(
+		'INT2'		=> 'INTEGER',
+		'SMALLINT'	=> 'INTEGER',
+		'INT'		=> 'BIGINT',
+		'INT4'		=> 'BIGINT',
+		'INTEGER'	=> 'BIGINT',
+		'INT8'		=> 'NUMERIC',
+		'BIGINT'	=> 'NUMERIC',
+		'REAL'		=> 'DOUBLE PRECISION',
+		'FLOAT'		=> 'DOUBLE PRECISION'
+	);
+
+	/**
+	 * NULL value representation in CREATE/ALTER TABLE statements
+	 *
+	 * @var	string
+	 */
+	protected $_null		= 'NULL';
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Class constructor
+	 *
+	 * @return	void
+	 */
+	public function __construct()
+	{
+		parent::__construct();
+
+		if (version_compare($this->db->version(), '9.0', '>'))
+		{
+			$this->create_table_if = 'CREATE TABLE IF NOT EXISTS';
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * ALTER TABLE
+	 *
+	 * @param	string	$alter_type	ALTER type
+	 * @param	string	$table		Table name
+	 * @param	mixed	$field		Column definition
+	 * @return	string|string[]
+	 */
+	protected function _alter_table($alter_type, $table, $field)
+ 	{
+		if (in_array($alter_type, array('DROP', 'ADD'), TRUE))
+		{
+			return parent::_alter_table($alter_type, $table, $field);
+		}
+
+		$sql = 'ALTER TABLE '.$this->db->escape_identifiers($table);
+		$sqls = array();
+		for ($i = 0, $c = count($field), $sql .= $alter_type.' '; $i < $c; $i++)
+		{
+			if ($field[$i]['_literal'] !== FALSE)
+			{
+				return FALSE;
+			}
+
+			if (version_compare($this->db->version(), '8', '>=') && isset($field[$i]['type']))
+			{
+				$sqls[] = $sql.' TYPE '.$field[$i]['type'].$field[$i]['length'];
+			}
+
+			if ( ! empty($field[$i]['default']))
+			{
+				$sqls[] = $sql.' ALTER '.$this->db->escape_identifiers($field[$i]['name'])
+					.' SET '.$field[$i]['default'];
+			}
+
+			if (isset($field[$i]['null']))
+			{
+				$sqls[] = $sql.' ALTER '.$this->db->escape_identifiers($field[$i]['name'])
+					.($field[$i]['null'] === TRUE ? ' DROP NOT NULL' : ' SET NOT NULL');
+			}
+
+			if ( ! empty($field[$i]['new_name']))
+			{
+				$sqls[] = $sql.' RENAME '.$this->db->escape_identifiers($field[$i]['name'])
+					.' TO '.$this->db->escape_identifiers($field[$i]['new_name']);
+			}
+		}
+
+		return $sqls;
+ 	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute TYPE
+	 *
+	 * Performs a data type mapping between different databases.
+	 *
+	 * @param	array	&$attributes
+	 * @return	void
+	 */
+	protected function _attr_type(&$attributes)
+	{
+		// Reset field lenghts for data types that don't support it
+		if (isset($attributes['CONSTRAINT']) && stripos($attributes['TYPE'], 'int') !== FALSE)
+		{
+			$attributes['CONSTRAINT'] = NULL;
+		}
+
+		switch (strtoupper($attributes['TYPE']))
+		{
+			case 'TINYINT':
+				$attributes['TYPE'] = 'SMALLINT';
+				$attributes['UNSIGNED'] = FALSE;
+				return;
+			case 'MEDIUMINT':
+				$attributes['TYPE'] = 'INTEGER';
+				$attributes['UNSIGNED'] = FALSE;
+				return;
+			default: return;
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute AUTO_INCREMENT
+	 *
+	 * @param	array	&$attributes
+	 * @param	array	&$field
+	 * @return	void
+	 */
+	protected function _attr_auto_increment(&$attributes, &$field)
+	{
+		if ( ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE)
+		{
+			$field['type'] = ($field['type'] === 'NUMERIC')
+						? 'BIGSERIAL'
+						: 'SERIAL';
+		}
+	}
+
+}
+
+/* End of file pdo_pgsql_forge.php */
+/* Location: ./system/database/drivers/pdo/subdrivers/pdo_pgsql_forge.php */
\ No newline at end of file
diff --git a/system/database/drivers/pdo/subdrivers/pdo_sqlite_forge.php b/system/database/drivers/pdo/subdrivers/pdo_sqlite_forge.php
new file mode 100644
index 000000000..414826212
--- /dev/null
+++ b/system/database/drivers/pdo/subdrivers/pdo_sqlite_forge.php
@@ -0,0 +1,228 @@
+<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP 5.1.6 or newer
+ *
+ * NOTICE OF LICENSE
+ *
+ * Licensed under the Open Software License version 3.0
+ *
+ * This source file is subject to the Open Software License (OSL 3.0) that is
+ * bundled with this package in the files license.txt / license.rst.  It is
+ * also available through the world wide web at this URL:
+ * http://opensource.org/licenses/OSL-3.0
+ * If you did not receive a copy of the license and are unable to obtain it
+ * through the world wide web, please send an email to
+ * licensing@ellislab.com so we can send you a copy immediately.
+ *
+ * @package		CodeIgniter
+ * @author		EllisLab Dev Team
+ * @copyright	Copyright (c) 2008 - 2012, EllisLab, Inc. (http://ellislab.com/)
+ * @license		http://opensource.org/licenses/OSL-3.0 Open Software License (OSL 3.0)
+ * @link		http://codeigniter.com
+ * @since		Version 2.1.0
+ * @filesource
+ */
+defined('BASEPATH') OR exit('No direct script access allowed');
+
+/**
+ * PDO SQLite Forge Class
+ *
+ * @category	Database
+ * @author		EllisLab Dev Team
+ * @link		http://codeigniter.com/user_guide/database/
+ */
+class CI_DB_pdo_sqlite_forge extends CI_DB_pdo_forge {
+
+	/**
+	 * CREATE TABLE IF statement
+	 *
+	 * @var	string
+	 */
+	protected $_create_table_if	= 'CREATE TABLE IF NOT EXISTS';
+
+	/**
+	 * DROP TABLE IF statement
+	 *
+	 * @var	string
+	 */
+	protected $_drop_table_if	= 'DROP TABLE IF EXISTS';
+
+	/**
+	 * UNSIGNED support
+	 *
+	 * @var	bool|array
+	 */
+	protected $_unsigned		= FALSE;
+
+	/**
+	 * NULL value representation in CREATE/ALTER TABLE statements
+	 *
+	 * @var	string
+	 */
+	protected $_null		= 'NULL';
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Class constructor
+	 *
+	 * @return	void
+	 */
+	public function __construct()
+	{
+		parent::__construct();
+
+		if (version_compare($this->db->version(), '3.3', '<'))
+		{
+			$this->_create_table_if = FALSE;
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Create database
+	 *
+	 * @param	string	$db_name	(ignored)
+	 * @return	bool
+	 */
+	public function create_database($db_name = '')
+	{
+		// In SQLite, a database is created when you connect to the database.
+		// We'll return TRUE so that an error isn't generated
+		return TRUE;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Drop database
+	 *
+	 * @param	string	$db_name	(ignored)
+	 * @return	bool
+	 */
+	public function drop_database($db_name = '')
+	{
+		// In SQLite, a database is dropped when we delete a file
+		if (@file_exists($this->db->database))
+		{
+			// We need to close the pseudo-connection first
+			$this->db->close();
+			if ( ! @unlink($this->db->database))
+			{
+				return $this->db->db_debug ? $this->db->display_error('db_unable_to_drop') : FALSE;
+			}
+			elseif ( ! empty($this->db->data_cache['db_names']))
+			{
+				$key = array_search(strtolower($this->db->database), array_map('strtolower', $this->db->data_cache['db_names']), TRUE);
+				if ($key !== FALSE)
+				{
+					unset($this->db->data_cache['db_names'][$key]);
+				}
+			}
+
+			return TRUE;
+		}
+
+		return $this->db->db_debug ? $this->db->display_error('db_unable_to_drop') : FALSE;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * ALTER TABLE
+	 *
+	 * @param	string	$alter_type	ALTER type
+	 * @param	string	$table		Table name
+	 * @param	mixed	$field		Column definition
+	 * @return	string|string[]
+	 */
+	protected function _alter_table($alter_type, $table, $field)
+	{
+		if ($alter_type === 'DROP' OR $alter_type === 'CHANGE')
+		{
+			// drop_column():
+			//	BEGIN TRANSACTION;
+			//	CREATE TEMPORARY TABLE t1_backup(a,b);
+			//	INSERT INTO t1_backup SELECT a,b FROM t1;
+			//	DROP TABLE t1;
+			//	CREATE TABLE t1(a,b);
+			//	INSERT INTO t1 SELECT a,b FROM t1_backup;
+			//	DROP TABLE t1_backup;
+			//	COMMIT;
+
+			return FALSE;
+		}
+
+		return parent::_alter_table($alter_type, $table, $field);
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Process column
+	 *
+	 * @param	array	$field
+	 * @return	string
+	 */
+	protected function _process_column($field)
+	{
+		return $this->db->escape_identifiers($field['name'])
+			.' '.$field['type']
+			.$field['auto_increment']
+			.$field['null']
+			.$field['unique']
+			.$field['default'];
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute TYPE
+	 *
+	 * Performs a data type mapping between different databases.
+	 *
+	 * @param	array	&$attributes
+	 * @return	void
+	 */
+	protected function _attr_type(&$attributes)
+	{
+		switch (strtoupper($attributes['TYPE']))
+		{
+			case 'ENUM':
+			case 'SET':
+				$attributes['TYPE'] = 'TEXT';
+				return;
+			default: return;
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute AUTO_INCREMENT
+	 *
+	 * @param	array	&$attributes
+	 * @param	array	&$field
+	 * @return	void
+	 */
+	protected function _attr_auto_increment(&$attributes, &$field)
+	{
+		if ( ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE && stripos($field['type'], 'int') !== FALSE)
+		{
+			$field['type'] = 'INTEGER PRIMARY KEY';
+			$field['default'] = '';
+			$field['null'] = '';
+			$field['unique'] = '';
+			$field['auto_increment'] = ' AUTOINCREMENT';
+
+			$this->primary_keys = array();
+		}
+	}
+
+}
+
+/* End of file pdo_sqlite_forge.php */
+/* Location: ./system/database/drivers/pdo/subdrivers/pdo_sqlite_forge.php */
\ No newline at end of file
diff --git a/system/database/drivers/pdo/subdrivers/pdo_sqlsrv_forge.php b/system/database/drivers/pdo/subdrivers/pdo_sqlsrv_forge.php
new file mode 100644
index 000000000..c62720d48
--- /dev/null
+++ b/system/database/drivers/pdo/subdrivers/pdo_sqlsrv_forge.php
@@ -0,0 +1,136 @@
+<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP 5.2.4 or newer
+ *
+ * NOTICE OF LICENSE
+ *
+ * Licensed under the Open Software License version 3.0
+ *
+ * This source file is subject to the Open Software License (OSL 3.0) that is
+ * bundled with this package in the files license.txt / license.rst.  It is
+ * also available through the world wide web at this URL:
+ * http://opensource.org/licenses/OSL-3.0
+ * If you did not receive a copy of the license and are unable to obtain it
+ * through the world wide web, please send an email to
+ * licensing@ellislab.com so we can send you a copy immediately.
+ *
+ * @package		CodeIgniter
+ * @author		EllisLab Dev Team
+ * @copyright	Copyright (c) 2008 - 2012, EllisLab, Inc. (http://ellislab.com/)
+ * @license		http://opensource.org/licenses/OSL-3.0 Open Software License (OSL 3.0)
+ * @link		http://codeigniter.com
+ * @since		Version 2.1.0
+ * @filesource
+ */
+defined('BASEPATH') OR exit('No direct script access allowed');
+
+/**
+ * PDO SQLSRV Forge Class
+ *
+ * @category	Database
+ * @author		EllisLab Dev Team
+ * @link		http://codeigniter.com/user_guide/database/
+ */
+class CI_DB_pdo_sqlsrv_forge extends CI_DB_pdo_forge {
+
+	/**
+	 * CREATE TABLE IF statement
+	 *
+	 * @var	string
+	 */
+	protected $_create_table_if	= "IF NOT EXISTS (SELECT * FROM sysobjects WHERE ID = object_id(N'%s') AND OBJECTPROPERTY(id, N'IsUserTable') = 1)\nCREATE TABLE";
+
+	/**
+	 * DROP TABLE IF statement
+	 *
+	 * @var	string
+	 */
+	protected $_drop_table_if	= "IF EXISTS (SELECT * FROM sysobjects WHERE ID = object_id(N'%s') AND OBJECTPROPERTY(id, N'IsUserTable') = 1)\nDROP TABLE";
+
+	/**
+	 * UNSIGNED support
+	 *
+	 * @var	array
+	 */
+	protected $_unsigned		= array(
+		'TINYINT'	=> 'SMALLINT',
+		'SMALLINT'	=> 'INT',
+		'INT'		=> 'BIGINT',
+		'REAL'		=> 'FLOAT'
+	);
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * ALTER TABLE
+	 *
+	 * @param	string	$alter_type	ALTER type
+	 * @param	string	$table		Table name
+	 * @param	mixed	$field		Column definition
+	 * @return	string|string[]
+	 */
+	protected function _alter_table($alter_type, $table, $field)
+	{
+		if (in_array($alter_type, array('ADD', 'DROP'), TRUE))
+		{
+			return parent::_alter_table($alter_type, $table, $field);
+		}
+
+		$sql = 'ALTER TABLE '.$this->db->escape_identifiers($table).' ALTER COLUMN ';
+		$sqls = array();
+		for ($i = 0, $c = count($field); $i < $c; $i++)
+		{
+			$sqls[] = $sql.$this->_process_column($field[$i]);
+		}
+
+		return $sqls;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute TYPE
+	 *
+	 * Performs a data type mapping between different databases.
+	 *
+	 * @param	array	&$attributes
+	 * @return	void
+	 */
+	protected function _attr_type(&$attributes)
+	{
+		switch (strtoupper($attributes['TYPE']))
+		{
+			case 'MEDIUMINT':
+				$attributes['TYPE'] = 'INTEGER';
+				$attributes['UNSIGNED'] = FALSE;
+				return;
+			case 'INTEGER':
+				$attributes['TYPE'] = 'INT';
+				return;
+			default: return;
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute AUTO_INCREMENT
+	 *
+	 * @param	array	&$attributes
+	 * @param	array	&$field
+	 * @return	void
+	 */
+	protected function _attr_auto_increment(&$attributes, &$field)
+	{
+		if ( ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE && stripos($field['type'], 'int') !== FALSE)
+		{
+			$field['auto_increment'] = ' IDENTITY(1,1)';
+		}
+	}
+
+}
+
+/* End of file pdo_sqlsrv_forge.php */
+/* Location: ./system/database/drivers/pdo/subdrivers/pdo_sqlsrv_forge.php */
\ No newline at end of file
diff --git a/system/database/drivers/postgre/postgre_driver.php b/system/database/drivers/postgre/postgre_driver.php
index 028dc1996..40f21b1e8 100644
--- a/system/database/drivers/postgre/postgre_driver.php
+++ b/system/database/drivers/postgre/postgre_driver.php
@@ -204,8 +204,12 @@ class CI_DB_postgre_driver extends CI_DB {
 		{
 			return $this->data_cache['version'];
 		}
+		elseif ( ! $this->conn_id)
+		{
+			$this->initialize();
+		}
 
-		if (($pg_version = pg_version($this->conn_id)) === FALSE)
+		if ( ! $this->conn_id OR ($pg_version = pg_version($this->conn_id)) === FALSE)
 		{
 			return FALSE;
 		}
diff --git a/system/database/drivers/postgre/postgre_forge.php b/system/database/drivers/postgre/postgre_forge.php
index b08fa5177..ad26763a4 100644
--- a/system/database/drivers/postgre/postgre_forge.php
+++ b/system/database/drivers/postgre/postgre_forge.php
@@ -36,188 +36,149 @@ defined('BASEPATH') OR exit('No direct script access allowed');
 class CI_DB_postgre_forge extends CI_DB_forge {
 
 	/**
-	 * DROP TABLE statement
+	 * UNSIGNED support
+	 *
+	 * @var	array
+	 */
+	protected $_unsigned		= array(
+		'INT2'		=> 'INTEGER',
+		'SMALLINT'	=> 'INTEGER',
+		'INT'		=> 'BIGINT',
+		'INT4'		=> 'BIGINT',
+		'INTEGER'	=> 'BIGINT',
+		'INT8'		=> 'NUMERIC',
+		'BIGINT'	=> 'NUMERIC',
+		'REAL'		=> 'DOUBLE PRECISION',
+		'FLOAT'		=> 'DOUBLE PRECISION'
+	);
+
+	/**
+	 * NULL value representation in CREATE/ALTER TABLE statements
 	 *
 	 * @var	string
 	 */
-	protected $_drop_table	= 'DROP TABLE IF EXISTS %s CASCADE';
+	protected $_null		= 'NULL';
 
 	// --------------------------------------------------------------------
 
 	/**
-	 * Process Fields
+	 * Class constructor
 	 *
-	 * @param	mixed	$fields
-	 * @param	array	$primary_keys
-	 * @return	string
+	 * @return	void
 	 */
-	protected function _process_fields($fields, $primary_keys = array())
+	public function __construct()
 	{
-		$sql = '';
-		$current_field_count = 0;
+		parent::__construct();
 
-		foreach ($fields as $field => $attributes)
+		if (version_compare($this->db->version(), '9.0', '>'))
 		{
-			// Numeric field names aren't allowed in databases, so if the key is
-			// numeric, we know it was assigned by PHP and the developer manually
-			// entered the field information, so we'll simply add it to the list
-			if (is_numeric($field))
+			$this->create_table_if = 'CREATE TABLE IF NOT EXISTS';
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * ALTER TABLE
+	 *
+	 * @param	string	$alter_type	ALTER type
+	 * @param	string	$table		Table name
+	 * @param	mixed	$field		Column definition
+	 * @return	string|string[]
+	 */
+	protected function _alter_table($alter_type, $table, $field)
+ 	{
+		if (in_array($alter_type, array('DROP', 'ADD'), TRUE))
+		{
+			return parent::_alter_table($alter_type, $table, $field);
+		}
+
+		$sql = 'ALTER TABLE '.$this->db->escape_identifiers($table);
+		$sqls = array();
+		for ($i = 0, $c = count($field), $sql .= $alter_type.' '; $i < $c; $i++)
+		{
+			if ($field[$i]['_literal'] !== FALSE)
 			{
-				$sql .= "\n\t".$attributes;
+				return FALSE;
 			}
-			else
+
+			if (version_compare($this->db->version(), '8', '>=') && isset($field[$i]['type']))
 			{
-				$sql .= "\n\t".$this->db->escape_identifiers($field);
-
-				$attributes = array_change_key_case($attributes, CASE_UPPER);
-				$is_unsigned = ( ! empty($attributes['UNSIGNED']) && $attributes['UNSIGNED'] === TRUE);
-
-				// Convert datatypes to be PostgreSQL-compatible
-				switch (strtoupper($attributes['TYPE']))
-				{
-					case 'TINYINT':
-						$attributes['TYPE'] = 'SMALLINT';
-						break;
-					case 'SMALLINT':
-						$attributes['TYPE'] = ($is_unsigned) ? 'INTEGER' : 'SMALLINT';
-						break;
-					case 'MEDIUMINT':
-						$attributes['TYPE'] = 'INTEGER';
-						break;
-					case 'INT':
-						$attributes['TYPE'] = ($is_unsigned) ? 'BIGINT' : 'INTEGER';
-						break;
-					case 'BIGINT':
-						$attributes['TYPE'] = ($is_unsigned) ? 'NUMERIC' : 'BIGINT';
-						break;
-					case 'DOUBLE':
-						$attributes['TYPE'] = 'DOUBLE PRECISION';
-						break;
-					case 'DATETIME':
-						$attributes['TYPE'] = 'TIMESTAMP';
-						break;
-					case 'LONGTEXT':
-						$attributes['TYPE'] = 'TEXT';
-						break;
-					case 'BLOB':
-						$attributes['TYPE'] = 'BYTEA';
-						break;
-					default:
-						break;
-				}
-
-				// If this is an auto-incrementing primary key, use the serial data type instead
-				$sql .= (in_array($field, $primary_keys) && ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE)
-					? ' SERIAL' : ' '.$attributes['TYPE'];
-
-				// Modified to prevent constraints with integer data types
-				if ( ! empty($attributes['CONSTRAINT']) && strpos($attributes['TYPE'], 'INT') === FALSE)
-				{
-					$sql .= '('.$attributes['CONSTRAINT'].')';
-				}
-
-				if (isset($attributes['DEFAULT']))
-				{
-					$sql .= " DEFAULT '".$attributes['DEFAULT']."'";
-				}
-
-				$sql .= ( ! empty($attributes['NULL']) && $attributes['NULL'] === TRUE)
-					? ' NULL' : ' NOT NULL';
-
-				// Added new attribute to create unique fields. Also works with MySQL
-				if ( ! empty($attributes['UNIQUE']) && $attributes['UNIQUE'] === TRUE)
-				{
-					$sql .= ' UNIQUE';
-				}
+				$sqls[] = $sql.' TYPE '.$field[$i]['type'].$field[$i]['length'];
 			}
 
-			// don't add a comma on the end of the last field
-			if (++$current_field_count < count($fields))
+			if ( ! empty($field[$i]['default']))
 			{
-				$sql .= ',';
+				$sqls[] = $sql.' ALTER '.$this->db->escape_identifiers($field[$i]['name'])
+					.' SET '.$field[$i]['default'];
+			}
+
+			if (isset($field[$i]['null']))
+			{
+				$sqls[] = $sql.' ALTER '.$this->db->escape_identifiers($field[$i]['name'])
+					.($field[$i]['null'] === TRUE ? ' DROP NOT NULL' : ' SET NOT NULL');
+			}
+
+			if ( ! empty($field[$i]['new_name']))
+			{
+				$sqls[] = $sql.' RENAME '.$this->db->escape_identifiers($field[$i]['name'])
+					.' TO '.$this->db->escape_identifiers($field[$i]['new_name']);
 			}
 		}
 
-		return $sql;
-	}
+		return $sqls;
+ 	}
 
 	// --------------------------------------------------------------------
 
 	/**
-	 * Create Table
+	 * Field attribute TYPE
 	 *
-	 * @param	string	the table name
-	 * @param	array	the fields
-	 * @param	mixed	primary key(s)
-	 * @param	mixed	key(s)
-	 * @param	bool	should 'IF NOT EXISTS' be added to the SQL
-	 * @return	bool
+	 * Performs a data type mapping between different databases.
+	 *
+	 * @param	array	&$attributes
+	 * @return	void
 	 */
-	protected function _create_table($table, $fields, $primary_keys, $keys, $if_not_exists)
+	protected function _attr_type(&$attributes)
 	{
-		$sql = 'CREATE TABLE ';
-
-		// PostgreSQL doesn't support IF NOT EXISTS syntax so we check if table exists manually
-		if ($if_not_exists === TRUE && $this->db->table_exists($table))
+		// Reset field lenghts for data types that don't support it
+		if (isset($attributes['CONSTRAINT']) && stripos($attributes['TYPE'], 'int') !== FALSE)
 		{
-			return TRUE;
+			$attributes['CONSTRAINT'] = NULL;
 		}
 
-		$sql .= $this->db->escape_identifiers($table).' ('.$this->_process_fields($fields, $primary_keys);
-
-		if (count($primary_keys) > 0)
+		switch (strtoupper($attributes['TYPE']))
 		{
-			$sql .= ",\n\tPRIMARY KEY (".implode(', ', $this->db->escape_identifiers($primary_keys)).')';
-		}
-
-		$sql .= "\n);";
-
-		if (is_array($keys) && count($keys) > 0)
-		{
-			foreach ($keys as $key)
-			{
-				$key = is_array($key)
-					? $this->db->escape_identifiers($key)
-					: array($this->db->escape_identifiers($key));
-
-				foreach ($key as $field)
-				{
-					$sql .= "\nCREATE INDEX ".$this->db->escape_identifiers($table.'_'.str_replace(array('"', "'"), '', $field).'_index')
-						.' ON '.$this->db->escape_identifiers($table).' ('.$this->db->escape_identifiers($field).');';
-				}
-			}
+			case 'TINYINT':
+				$attributes['TYPE'] = 'SMALLINT';
+				$attributes['UNSIGNED'] = FALSE;
+				return;
+			case 'MEDIUMINT':
+				$attributes['TYPE'] = 'INTEGER';
+				$attributes['UNSIGNED'] = FALSE;
+				return;
+			default: return;
 		}
-
-		return $sql;
 	}
 
 	// --------------------------------------------------------------------
 
 	/**
-	 * Alter table query
-	 *
-	 * Generates a platform-specific query so that a table can be altered
-	 * Called by add_column(), drop_column(), and column_alter(),
+	 * Field attribute AUTO_INCREMENT
 	 *
-	 * @param	string	$alter_type	the ALTER type (ADD, DROP, CHANGE)
-	 * @param	string	$table		the table name
-	 * @param	string	$fields		the column definition
-	 * @param	string	$after_field
-	 * @return	string
+	 * @param	array	&$attributes
+	 * @param	array	&$field
+	 * @return	void
 	 */
-	protected function _alter_table($alter_type, $table, $fields, $after_field = '')
- 	{
- 		$sql = 'ALTER TABLE '.$this->db->escape_identifiers($table).' '.$alter_type.' ';
-
- 		// DROP has everything it needs now.
- 		if ($alter_type === 'DROP')
- 		{
- 			return $sql.$this->db->escape_identifiers($fields);
- 		}
-
- 		return $sql.$this->_process_fields($fields)
-			.($after_field !== '' ? ' AFTER '.$this->db->escape_identifiers($after_field) : '');
- 	}
+	protected function _attr_auto_increment(&$attributes, &$field)
+	{
+		if ( ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE)
+		{
+			$field['type'] = ($field['type'] === 'NUMERIC')
+						? 'BIGSERIAL'
+						: 'SERIAL';
+		}
+	}
 
 }
 
diff --git a/system/database/drivers/sqlite/sqlite_forge.php b/system/database/drivers/sqlite/sqlite_forge.php
index 5650af7be..6ad583560 100644
--- a/system/database/drivers/sqlite/sqlite_forge.php
+++ b/system/database/drivers/sqlite/sqlite_forge.php
@@ -36,9 +36,32 @@ defined('BASEPATH') OR exit('No direct script access allowed');
 class CI_DB_sqlite_forge extends CI_DB_forge {
 
 	/**
+	 * CREATE TABLE IF statement
+	 *
+	 * @var	string
+	 */
+	protected $_create_table_if	= FALSE;
+
+	/**
+	 * UNSIGNED support
+	 *
+	 * @var	bool|array
+	 */
+	protected $_unsigned		= FALSE;
+
+	/**
+	 * NULL value representation in CREATE/ALTER TABLE statements
+	 *
+	 * @var	string
+	 */
+	protected $_null		= 'NULL';
+
+	// --------------------------------------------------------------------
+
+	/**
 	 * Create database
 	 *
-	 * @param	string	the database name
+	 * @param	string	$db_name	(ignored)
 	 * @return	bool
 	 */
 	public function create_database($db_name = '')
@@ -53,7 +76,7 @@ class CI_DB_sqlite_forge extends CI_DB_forge {
 	/**
 	 * Drop database
 	 *
-	 * @param	string	the database name (ignored)
+	 * @param	string	$db_name	(ignored)
 	 * @return	bool
 	 */
 	public function drop_database($db_name = '')
@@ -77,126 +100,95 @@ class CI_DB_sqlite_forge extends CI_DB_forge {
 	// --------------------------------------------------------------------
 
 	/**
-	 * Create Table
+	 * ALTER TABLE
 	 *
-	 * @param	string	the table name
-	 * @param	array	the fields
-	 * @param	mixed	primary key(s)
-	 * @param	mixed	key(s)
-	 * @param	bool	should 'IF NOT EXISTS' be added to the SQL
-	 * @return	bool
+	 * @todo	implement drop_column(), modify_column()
+	 * @param	string	$alter_type	ALTER type
+	 * @param	string	$table		Table name
+	 * @param	mixed	$field		Column definition
+	 * @return	string|string[]
 	 */
-	protected function _create_table($table, $fields, $primary_keys, $keys, $if_not_exists)
+	protected function _alter_table($alter_type, $table, $field)
 	{
-		$sql = 'CREATE TABLE ';
-
-		// IF NOT EXISTS added to SQLite in 3.3.0
-		if ($if_not_exists === TRUE && version_compare($this->db->version(), '3.3.0', '>=') === TRUE)
+		if ($alter_type === 'DROP' OR $alter_type === 'CHANGE')
 		{
-			$sql .= 'IF NOT EXISTS ';
-		}
-
-		$sql .= $this->db->escape_identifiers($table).' (';
-		$current_field_count = 0;
-
-		foreach ($fields as $field => $attributes)
-		{
-			// Numeric field names aren't allowed in databases, so if the key is
-			// numeric, we know it was assigned by PHP and the developer manually
-			// entered the field information, so we'll simply add it to the list
-			if (is_numeric($field))
-			{
-				$sql .= "\n\t".$attributes;
-			}
-			else
-			{
-				$attributes = array_change_key_case($attributes, CASE_UPPER);
-
-				$sql .= "\n\t".$this->db->escape_identifiers($field).' '.$attributes['TYPE'];
-
-				empty($attributes['CONSTRAINT']) OR $sql .= '('.$attributes['CONSTRAINT'].')';
-
-				if ( ! empty($attributes['UNSIGNED']) && $attributes['UNSIGNED'] === TRUE)
-				{
-					$sql .= ' UNSIGNED';
-				}
-
-				if (isset($attributes['DEFAULT']))
-				{
-					$sql .= " DEFAULT '".$attributes['DEFAULT']."'";
-				}
+			// drop_column():
+			//	BEGIN TRANSACTION;
+			//	CREATE TEMPORARY TABLE t1_backup(a,b);
+			//	INSERT INTO t1_backup SELECT a,b FROM t1;
+			//	DROP TABLE t1;
+			//	CREATE TABLE t1(a,b);
+			//	INSERT INTO t1 SELECT a,b FROM t1_backup;
+			//	DROP TABLE t1_backup;
+			//	COMMIT;
 
+			return FALSE;
+		}
 
-				$sql .= ( ! empty($attributes['NULL']) && $attributes['NULL'] === TRUE)
-					? ' NULL' : ' NOT NULL';
+		return parent::_alter_table($alter_type, $table, $field);
+	}
 
-				if ( ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE)
-				{
-					$sql .= ' AUTO_INCREMENT';
-				}
-			}
+	// --------------------------------------------------------------------
 
-			// don't add a comma on the end of the last field
-			if (++$current_field_count < count($fields))
-			{
-				$sql .= ',';
-			}
-		}
+	/**
+	 * Process column
+	 *
+	 * @param	array	$field
+	 * @return	string
+	 */
+	protected function _process_column($field)
+	{
+		return $this->db->escape_identifiers($field['name'])
+			.' '.$field['type']
+			.$field['auto_increment']
+			.$field['null']
+			.$field['unique']
+			.$field['default'];
+	}
 
-		if (count($primary_keys) > 0)
-		{
-			$sql .= ",\n\tPRIMARY KEY (".implode(', ', $this->db->escape_identifiers($primary_keys)).')';
-		}
+	// --------------------------------------------------------------------
 
-		if (is_array($keys) && count($keys) > 0)
+	/**
+	 * Field attribute TYPE
+	 *
+	 * Performs a data type mapping between different databases.
+	 *
+	 * @param	array	&$attributes
+	 * @return	void
+	 */
+	protected function _attr_type(&$attributes)
+	{
+		switch (strtoupper($attributes['TYPE']))
 		{
-			foreach ($keys as $key)
-			{
-				$key = is_array($key)
-					? $this->db->escape_identifiers($key)
-					: array($this->db->escape_identifiers($key));
-
-				$sql .= ",\n\tUNIQUE (".implode(', ', $key).')';
-			}
+			case 'ENUM':
+			case 'SET':
+				$attributes['TYPE'] = 'TEXT';
+				return;
+			default: return;
 		}
-
-		return $sql."\n)";
 	}
 
 	// --------------------------------------------------------------------
 
 	/**
-	 * Alter table query
+	 * Field attribute AUTO_INCREMENT
 	 *
-	 * Generates a platform-specific query so that a table can be altered
-	 * Called by add_column(), drop_column(), and column_alter(),
-	 *
-	 * @param	string	the ALTER type (ADD, DROP, CHANGE)
-	 * @param	string	the column name
-	 * @param	string	the table name
-	 * @param	string	the column definition
-	 * @param	string	the default value
-	 * @param	bool	should 'NOT NULL' be added
-	 * @param	string	the field after which we should add the new field
-	 * @return	string
+	 * @param	array	&$attributes
+	 * @param	array	&$field
+	 * @return	void
 	 */
-	protected function _alter_table($alter_type, $table, $column_name, $column_definition = '', $default_value = '', $null = '', $after_field = '')
+	protected function _attr_auto_increment(&$attributes, &$field)
 	{
-		/* SQLite only supports adding new columns and it does
-		 * NOT support the AFTER statement. Each new column will
-		 * be added as the last one in the table.
-		 */
-		if ($alter_type !== 'ADD COLUMN')
+		if ( ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE && stripos($field['type'], 'int') !== FALSE)
 		{
-			// Not supported
-			return FALSE;
-		}
+			$field['type'] = 'INTEGER PRIMARY KEY';
+			$field['default'] = '';
+			$field['null'] = '';
+			$field['unique'] = '';
+			$field['auto_increment'] = ' AUTOINCREMENT';
 
-		return 'ALTER TABLE '.$this->db->escape_identifiers($table).' '.$alter_type.' '.$this->db->escape_identifiers($column_name)
-			.' '.$column_definition
-			.($default_value != '' ? " DEFAULT '".$default_value."'" : '')
-			// If NOT NULL is specified, the field must have a DEFAULT value other than NULL
-			.(($null !== NULL && $default_value !== 'NULL') ? ' NOT NULL' : ' NULL');
+			$this->primary_keys = array();
+		}
 	}
 
 }
diff --git a/system/database/drivers/sqlite3/sqlite3_forge.php b/system/database/drivers/sqlite3/sqlite3_forge.php
index e1dd3fa91..7ba0f7bab 100644
--- a/system/database/drivers/sqlite3/sqlite3_forge.php
+++ b/system/database/drivers/sqlite3/sqlite3_forge.php
@@ -36,9 +36,42 @@ defined('BASEPATH') OR exit('No direct script access allowed');
 class CI_DB_sqlite3_forge extends CI_DB_forge {
 
 	/**
+	 * UNSIGNED support
+	 *
+	 * @var	bool|array
+	 */
+	protected $_unsigned		= FALSE;
+
+	/**
+	 * NULL value representation in CREATE/ALTER TABLE statements
+	 *
+	 * @var	string
+	 */
+	protected $_null		= 'NULL';
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Class constructor
+	 *
+	 * @return	void
+	 */
+	public function __construct()
+	{
+		parent::__construct();
+
+		if (version_compare($this->db->version(), '3.3', '<'))
+		{
+			$this->create_table_if = FALSE;
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
 	 * Create database
 	 *
-	 * @param	string	the database name
+	 * @param	string	$db_name
 	 * @return	bool
 	 */
 	public function create_database($db_name = '')
@@ -53,7 +86,7 @@ class CI_DB_sqlite3_forge extends CI_DB_forge {
 	/**
 	 * Drop database
 	 *
-	 * @param	string	the database name (ignored)
+	 * @param	string	$db_name	(ignored)
 	 * @return	bool
 	 */
 	public function drop_database($db_name = '')
@@ -85,125 +118,95 @@ class CI_DB_sqlite3_forge extends CI_DB_forge {
 	// --------------------------------------------------------------------
 
 	/**
-	 * Create Table
+	 * ALTER TABLE
 	 *
-	 * @param	string	the table name
-	 * @param	array	the fields
-	 * @param	mixed	primary key(s)
-	 * @param	mixed	key(s)
-	 * @param	bool	should 'IF NOT EXISTS' be added to the SQL
-	 * @return	bool
+	 * @todo	implement drop_column(), modify_column()
+	 * @param	string	$alter_type	ALTER type
+	 * @param	string	$table		Table name
+	 * @param	mixed	$field		Column definition
+	 * @return	string|string[]
 	 */
-	protected function _create_table($table, $fields, $primary_keys, $keys, $if_not_exists)
+	protected function _alter_table($alter_type, $table, $field)
 	{
-		$sql = 'CREATE TABLE ';
-
-		// IF NOT EXISTS added to SQLite in 3.3.0
-		if ($if_not_exists === TRUE && version_compare($this->db->version(), '3.3.0', '>=') === TRUE)
-		{
-			$sql .= 'IF NOT EXISTS ';
-		}
-
-		$sql .= $this->db->escape_identifiers($table).' (';
-		$current_field_count = 0;
-
-		foreach ($fields as $field => $attributes)
+		if ($alter_type === 'DROP' OR $alter_type === 'CHANGE')
 		{
-			// Numeric field names aren't allowed in databases, so if the key is
-			// numeric, we know it was assigned by PHP and the developer manually
-			// entered the field information, so we'll simply add it to the list
-			if (is_numeric($field))
-			{
-				$sql .= "\n\t".$attributes;
-			}
-			else
-			{
-				$attributes = array_change_key_case($attributes, CASE_UPPER);
-
-				$sql .= "\n\t".$this->db->escape_identifiers($field).' '.$attributes['TYPE'];
-
-				empty($attributes['CONSTRAINT']) OR $sql .= '('.$attributes['CONSTRAINT'].')';
-
-				if ( ! empty($attributes['UNSIGNED']) && $attributes['UNSIGNED'] === TRUE)
-				{
-					$sql .= ' UNSIGNED';
-				}
+			// drop_column():
+			//	BEGIN TRANSACTION;
+			//	CREATE TEMPORARY TABLE t1_backup(a,b);
+			//	INSERT INTO t1_backup SELECT a,b FROM t1;
+			//	DROP TABLE t1;
+			//	CREATE TABLE t1(a,b);
+			//	INSERT INTO t1 SELECT a,b FROM t1_backup;
+			//	DROP TABLE t1_backup;
+			//	COMMIT;
 
-				if (isset($attributes['DEFAULT']))
-				{
-					$sql .= " DEFAULT '".$attributes['DEFAULT']."'";
-				}
+			return FALSE;
+		}
 
-				$sql .= ( ! empty($attributes['NULL']) && $attributes['NULL'] === TRUE)
-					? ' NULL' : ' NOT NULL';
+		return parent::_alter_table($alter_type, $table, $field);
+	}
 
-				if ( ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE)
-				{
-					$sql .= ' AUTO_INCREMENT';
-				}
-			}
+	// --------------------------------------------------------------------
 
-			// don't add a comma on the end of the last field
-			if (++$current_field_count < count($fields))
-			{
-				$sql .= ',';
-			}
-		}
+	/**
+	 * Process column
+	 *
+	 * @param	array	$field
+	 * @return	string
+	 */
+	protected function _process_column($field)
+	{
+		return $this->db->escape_identifiers($field['name'])
+			.' '.$field['type']
+			.$field['auto_increment']
+			.$field['null']
+			.$field['unique']
+			.$field['default'];
+	}
 
-		if (count($primary_keys) > 0)
-		{
-			$sql .= ",\n\tPRIMARY KEY (".implode(', ', $this->db->escape_identifiers($primary_keys)).')';
-		}
+	// --------------------------------------------------------------------
 
-		if (is_array($keys) && count($keys) > 0)
+	/**
+	 * Field attribute TYPE
+	 *
+	 * Performs a data type mapping between different databases.
+	 *
+	 * @param	array	&$attributes
+	 * @return	void
+	 */
+	protected function _attr_type(&$attributes)
+	{
+		switch (strtoupper($attributes['TYPE']))
 		{
-			foreach ($keys as $key)
-			{
-				$key = is_array($key)
-					? $this->db->escape_identifiers($key)
-					: array($this->db->escape_identifiers($key));
-
-				$sql .= ",\n\tUNIQUE (".implode(', ', $key).')';
-			}
+			case 'ENUM':
+			case 'SET':
+				$attributes['TYPE'] = 'TEXT';
+				return;
+			default: return;
 		}
-
-		return $sql."\n)";
 	}
 
 	// --------------------------------------------------------------------
 
 	/**
-	 * Alter table query
-	 *
-	 * Generates a platform-specific query so that a table can be altered
-	 * Called by add_column(), drop_column(), and column_alter(),
+	 * Field attribute AUTO_INCREMENT
 	 *
-	 * @param	string	the ALTER type (ADD, DROP, CHANGE)
-	 * @param	string	the column name
-	 * @param	string	the table name
-	 * @param	string	the column definition
-	 * @param	string	the default value
-	 * @param	bool	should 'NOT NULL' be added
-	 * @param	string	the field after which we should add the new field
-	 * @return	string
+	 * @param	array	&$attributes
+	 * @param	array	&$field
+	 * @return	void
 	 */
-	protected function _alter_table($alter_type, $table, $column_name, $column_definition = '', $default_value = '', $null = '', $after_field = '')
+	protected function _attr_auto_increment(&$attributes, &$field)
 	{
-		/* SQLite only supports adding new columns and it does
-		 * NOT support the AFTER statement. Each new column will
-		 * be added as the last one in the table.
-		 */
-		if ($alter_type !== 'ADD COLUMN')
+		if ( ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE && stripos($field['type'], 'int') !== FALSE)
 		{
-			// Not supported
-			return FALSE;
-		}
+			$field['type'] = 'INTEGER PRIMARY KEY';
+			$field['default'] = '';
+			$field['null'] = '';
+			$field['unique'] = '';
+			$field['auto_increment'] = ' AUTOINCREMENT';
 
-		return 'ALTER TABLE '.$this->db->escape_identifiers($table).' '.$alter_type.' '.$this->db->escape_identifiers($column_name)
-			.' '.$column_definition
-			.($default_value !== '' ? ' DEFAULT '.$default_value : '')
-			// If NOT NULL is specified, the field must have a DEFAULT value other than NULL
-			.(($null !== NULL && $default_value !== 'NULL') ? ' NOT NULL' : ' NULL');
+			$this->primary_keys = array();
+		}
 	}
 
 }
diff --git a/system/database/drivers/sqlsrv/sqlsrv_driver.php b/system/database/drivers/sqlsrv/sqlsrv_driver.php
index de3d87312..d3999bf75 100644
--- a/system/database/drivers/sqlsrv/sqlsrv_driver.php
+++ b/system/database/drivers/sqlsrv/sqlsrv_driver.php
@@ -275,8 +275,12 @@ class CI_DB_sqlsrv_driver extends CI_DB {
 		{
 			return $this->data_cache['version'];
 		}
+		elseif ( ! $this->conn_id)
+		{
+			$this->initialize();
+		}
 
-		if (($info = sqlsrv_server_info($this->conn_id)) === FALSE)
+		if ( ! $this->conn_id OR ($info = sqlsrv_server_info($this->conn_id)) === FALSE)
 		{
 			return FALSE;
 		}
diff --git a/system/database/drivers/sqlsrv/sqlsrv_forge.php b/system/database/drivers/sqlsrv/sqlsrv_forge.php
index 8155565c0..da8f68c56 100644
--- a/system/database/drivers/sqlsrv/sqlsrv_forge.php
+++ b/system/database/drivers/sqlsrv/sqlsrv_forge.php
@@ -36,130 +36,98 @@ defined('BASEPATH') OR exit('No direct script access allowed');
 class CI_DB_sqlsrv_forge extends CI_DB_forge {
 
 	/**
-	 * DROP TABLE statement
+	 * CREATE TABLE IF statement
 	 *
 	 * @var	string
 	 */
-	protected $_drop_table	= 'DROP TABLE %s';
-
-	// --------------------------------------------------------------------
+	protected $_create_table_if	= "IF NOT EXISTS (SELECT * FROM sysobjects WHERE ID = object_id(N'%s') AND OBJECTPROPERTY(id, N'IsUserTable') = 1)\nCREATE TABLE";
 
 	/**
-	 * Create Table
+	 * DROP TABLE IF statement
 	 *
-	 * @param	string	the table name
-	 * @param	array	the fields
-	 * @param	mixed	primary key(s)
-	 * @param	mixed	key(s)
-	 * @param	bool	should 'IF NOT EXISTS' be added to the SQL
-	 * @return	string
+	 * @var	string
 	 */
-	protected function _create_table($table, $fields, $primary_keys, $keys, $if_not_exists)
-	{
-		$sql = ($if_not_exists === TRUE)
-			? "IF NOT EXISTS (SELECT * FROM sysobjects WHERE ID = object_id(N'".$table."') AND OBJECTPROPERTY(id, N'IsUserTable') = 1)\n"
-			: '';
-
-		$sql .= 'CREATE TABLE '.$this->db->escape_identifiers($table).' (';
-
-		$current_field_count = 0;
-		foreach ($fields as $field => $attributes)
-		{
-			// Numeric field names aren't allowed in databases, so if the key is
-			// numeric, we know it was assigned by PHP and the developer manually
-			// entered the field information, so we'll simply add it to the list
-			if (is_numeric($field))
-			{
-				$sql .= "\n\t".$attributes;
-			}
-			else
-			{
-				$attributes = array_change_key_case($attributes, CASE_UPPER);
-
-				$sql .= "\n\t".$this->db->escape_identifiers($field).' '.$attributes['TYPE'];
+	protected $_drop_table_if	= "IF EXISTS (SELECT * FROM sysobjects WHERE ID = object_id(N'%s') AND OBJECTPROPERTY(id, N'IsUserTable') = 1)\nDROP TABLE";
 
-				if (stripos($attributes['TYPE'], 'INT') === FALSE && ! empty($attributes['CONSTRAINT']))
-				{
-					$sql .= '('.$attributes['CONSTRAINT'].')';
-				}
-
-				if ( ! empty($attributes['UNSIGNED']) && $attributes['UNSIGNED'] === TRUE)
-				{
-					$sql .= ' UNSIGNED';
-				}
-
-				if (isset($attributes['DEFAULT']))
-				{
-					$sql .= " DEFAULT '".$attributes['DEFAULT']."'";
-				}
-
-				$sql .= ( ! empty($attributes['NULL']) && $attribues['NULL'] === TRUE)
-					? ' NULL' : ' NOT NULL';
-
-				if ( ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE)
-				{
-					$sql .= ' AUTO_INCREMENT';
-				}
-			}
+	/**
+	 * UNSIGNED support
+	 *
+	 * @var	array
+	 */
+	protected $_unsigned		= array(
+		'TINYINT'	=> 'SMALLINT',
+		'SMALLINT'	=> 'INT',
+		'INT'		=> 'BIGINT',
+		'REAL'		=> 'FLOAT'
+	);
 
-			// don't add a comma on the end of the last field
-			if (++$current_field_count < count($fields))
-			{
-				$sql .= ',';
-			}
-		}
+	// --------------------------------------------------------------------
 
-		if (count($primary_keys) > 0)
+	/**
+	 * ALTER TABLE
+	 *
+	 * @param	string	$alter_type	ALTER type
+	 * @param	string	$table		Table name
+	 * @param	mixed	$field		Column definition
+	 * @return	string|string[]
+	 */
+	protected function _alter_table($alter_type, $table, $field)
+	{
+		if (in_array($alter_type, array('ADD', 'DROP'), TRUE))
 		{
-			$sql .= ",\n\tPRIMARY KEY (".implode(', ', $this->db->escape_identifiers($primary_keys)).')';
+			return parent::_alter_table($alter_type, $table, $field);
 		}
 
-		if (is_array($keys) && count($keys) > 0)
+		$sql = 'ALTER TABLE '.$this->db->escape_identifiers($table).' ALTER COLUMN ';
+		$sqls = array();
+		for ($i = 0, $c = count($field); $i < $c; $i++)
 		{
-			foreach ($keys as $key)
-			{
-				$key = is_array($key)
-					? $this->db->escape_identifiers($key)
-					: array($this->escape_identifiers($key));
-
-				$sql .= ",\n\tFOREIGN KEY (".implode(', ', $key).')';
-			}
+			$sqls[] = $sql.$this->_process_column($field[$i]);
 		}
 
-		return $sql."\n)";
+		return $sqls;
 	}
 
 	// --------------------------------------------------------------------
 
 	/**
-	 * Alter table query
+	 * Field attribute TYPE
 	 *
-	 * Generates a platform-specific query so that a table can be altered
-	 * Called by add_column(), drop_column(), and column_alter(),
+	 * Performs a data type mapping between different databases.
 	 *
-	 * @param	string	the ALTER type (ADD, DROP, CHANGE)
-	 * @param	string	the column name
-	 * @param	string	the table name
-	 * @param	string	the column definition
-	 * @param	string	the default value
-	 * @param	bool	should 'NOT NULL' be added
-	 * @param	string	the field after which we should add the new field
-	 * @return	string
+	 * @param	array	&$attributes
+	 * @return	void
 	 */
-	protected function _alter_table($alter_type, $table, $column_name, $column_definition = '', $default_value = '', $null = '', $after_field = '')
+	protected function _attr_type(&$attributes)
 	{
-		$sql = 'ALTER TABLE '.$this->db->escape_identifiers($table).' '.$alter_type.' '.$this->db->escape_identifiers($column_name);
-
-		// DROP has everything it needs now.
-		if ($alter_type === 'DROP')
+		switch (strtoupper($attributes['TYPE']))
 		{
-			return $sql;
+			case 'MEDIUMINT':
+				$attributes['TYPE'] = 'INTEGER';
+				$attributes['UNSIGNED'] = FALSE;
+				return;
+			case 'INTEGER':
+				$attributes['TYPE'] = 'INT';
+				return;
+			default: return;
 		}
+	}
 
-		return $sql.' '.$column_definition
-			.($default_value != '' ? ' DEFAULT "'.$default_value.'"' : '')
-			.($null === NULL ? ' NULL' : ' NOT NULL')
-			.($after_field != '' ? ' AFTER '.$this->db->escape_identifiers($after_field) : '');
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field attribute AUTO_INCREMENT
+	 *
+	 * @param	array	&$attributes
+	 * @param	array	&$field
+	 * @return	void
+	 */
+	protected function _attr_auto_increment(&$attributes, &$field)
+	{
+		if ( ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE && stripos($field['type'], 'int') !== FALSE)
+		{
+			$field['auto_increment'] = ' IDENTITY(1,1)';
+		}
 	}
 
 }
diff --git a/system/libraries/Form_validation.php b/system/libraries/Form_validation.php
index 50708c7d8..e50eee4f2 100644
--- a/system/libraries/Form_validation.php
+++ b/system/libraries/Form_validation.php
@@ -440,11 +440,10 @@ class CI_Form_validation {
 		// Load the language file containing error messages
 		$this->CI->lang->load('form_validation');
 
-		// Cycle through the rules for each field, match the
-		// corresponding $_POST item and test for errors
+		// Cycle through the rules for each field and match the corresponding $validation_data item
 		foreach ($this->_field_data as $field => $row)
 		{
-			// Fetch the data from the corresponding $_POST or validation array and cache it in the _field_data array.
+			// Fetch the data from the validation_data array item and cache it in the _field_data array.
 			// Depending on whether the field name is an array or a string will determine where we get it from.
 			if ($row['is_array'] === TRUE)
 			{
@@ -454,7 +453,13 @@ class CI_Form_validation {
 			{
 				$this->_field_data[$field]['postdata'] = $validation_array[$field];
 			}
+		}
 
+		// Execute validation rules
+		// Note: A second foreach (for now) is required in order to avoid false-positives
+		//	 for rules like 'matches', which correlate to other validation fields.
+		foreach ($this->_field_data as $field => $row)
+		{
 			// Don't try to validate if we have no rules set
 			if (empty($row['rules']))
 			{
diff --git a/system/libraries/Log.php b/system/libraries/Log.php
index a4dd47f86..e66270840 100644
--- a/system/libraries/Log.php
+++ b/system/libraries/Log.php
@@ -152,7 +152,7 @@ class CI_Log {
 		if ( ! file_exists($filepath))
 		{
 			$newfile = TRUE;
-			$message .= '<'."?php if defined('BASEPATH') OR exit('No direct script access allowed'); ?".">\n\n";
+			$message .= '<'."?php defined('BASEPATH') OR exit('No direct script access allowed'); ?".">\n\n";
 		}
 
 		if ( ! $fp = @fopen($filepath, FOPEN_WRITE_CREATE))
diff --git a/tests/codeigniter/core/Loader_test.php b/tests/codeigniter/core/Loader_test.php
index be223f97d..ecc5ca933 100644
--- a/tests/codeigniter/core/Loader_test.php
+++ b/tests/codeigniter/core/Loader_test.php
@@ -493,7 +493,7 @@ class Loader_test extends CI_TestCase {
 		);
 		$this->ci_vfs_create('autoload', '<?php $autoload = '.var_export($cfg, TRUE).';', $this->ci_app_root, 'config');
 
-		$this->load->__construct();
+		$this->load->initialize();
 
 		// Verify path
 		$this->assertContains($path, $this->load->get_package_paths());
diff --git a/tests/mocks/ci_testcase.php b/tests/mocks/ci_testcase.php
index 2d0a26830..f16492945 100644
--- a/tests/mocks/ci_testcase.php
+++ b/tests/mocks/ci_testcase.php
@@ -39,8 +39,6 @@ class CI_TestCase extends PHPUnit_Framework_TestCase {
 		$this->ci_app_root = vfsStream::newDirectory('application')->at($this->ci_vfs_root);
 		$this->ci_base_root = vfsStream::newDirectory('system')->at($this->ci_vfs_root);
 		$this->ci_view_root = vfsStream::newDirectory('views')->at($this->ci_app_root);
-		vfsStream::newDirectory('config')->at($this->ci_app_root);
-		$this->ci_vfs_clone('application/config/autoload.php');
 
 		if (method_exists($this, 'set_up'))
 		{
diff --git a/tests/mocks/database/db/driver.php b/tests/mocks/database/db/driver.php
index 65ac2c4cc..2cf54b97b 100644
--- a/tests/mocks/database/db/driver.php
+++ b/tests/mocks/database/db/driver.php
@@ -34,6 +34,7 @@ class Mock_Database_DB_Driver extends CI_DB_driver {
 
 		return call_user_func_array(array($this->ci_db_driver, $method), $arguments);
 	}
+
 }
 
 class CI_DB extends Mock_Database_DB_QueryBuilder {}
\ No newline at end of file
diff --git a/tests/mocks/database/schema/skeleton.php b/tests/mocks/database/schema/skeleton.php
index d72244528..e5c536090 100644
--- a/tests/mocks/database/schema/skeleton.php
+++ b/tests/mocks/database/schema/skeleton.php
@@ -69,7 +69,7 @@ class Mock_Database_Schema_Skeleton {
 			)
 		));
 		static::$forge->add_key('id', TRUE);
-		static::$forge->create_table('user', (strpos(static::$driver, 'pgsql') === FALSE));
+		static::$forge->create_table('user', TRUE);
 
 		// Job Table
 		static::$forge->add_field(array(
@@ -86,7 +86,7 @@ class Mock_Database_Schema_Skeleton {
 			)
 		));
 		static::$forge->add_key('id', TRUE);
-		static::$forge->create_table('job', (strpos(static::$driver, 'pgsql') === FALSE));
+		static::$forge->create_table('job', TRUE);
 
 		// Misc Table
 		static::$forge->add_field(array(
@@ -103,7 +103,7 @@ class Mock_Database_Schema_Skeleton {
 			)
 		));
 		static::$forge->add_key('id', TRUE);
-		static::$forge->create_table('misc', (strpos(static::$driver, 'pgsql') === FALSE));
+		static::$forge->create_table('misc', TRUE);
 	}
 
 	/**
diff --git a/user_guide_src/source/changelog.rst b/user_guide_src/source/changelog.rst
index abb75f579..717d7f6ba 100644
--- a/user_guide_src/source/changelog.rst
+++ b/user_guide_src/source/changelog.rst
@@ -154,6 +154,8 @@ Release Date: Not Released
    -  Added MySQL client compression support.
    -  Added encrypted connections support (for *mysql*, *sqlsrv* and PDO with *sqlsrv*).
    -  Removed :doc:`Loader Class <libraries/loader>` from Database error tracing to better find the likely culprit.
+   -  Added an optional second parameter to ``drop_table()`` in :doc:`Database Forge <database/forge>` that allows adding the IF EXISTS condition.
+   -  Removed the optional AFTER clause from :doc:`Database Forge <database/forge>` method ``add_column()``.
 
 -  Libraries
 
@@ -182,7 +184,7 @@ Release Date: Not Released
 	 -  Added method ``remove()`` to remove a cart item, updating with quantity of 0 seemed like a hack but has remained to retain compatibility.
 	 -  Added method ``get_item()`` to enable retrieving data for a single cart item.
    -  :doc:`Image Manipulation library <libraries/image_lib>` changes include:
-	 -  The initialize() method now only sets existing class properties.
+	 -  The ``initialize()`` method now only sets existing class properties.
 	 -  Added support for 3-length hex color values for *wm_font_color* and *wm_shadow_color* properties, as well as validation for them.
 	 -  Class properties *wm_font_color*, *wm_shadow_color* and *wm_use_drop_shadow* are now protected, to avoid breaking the ``text_watermark()`` method if they are set manually after initialization.
 	 -  If property *maintain_ratio* is set to TRUE, ``image_reproportion()`` now doesn't need both width and height to be specified.
@@ -245,7 +247,6 @@ Release Date: Not Released
 	 -  ``library()`` method will now load drivers as well, for backward compatibility of converted libraries (like :doc:`Session <libraries/sessions>`).
 	 -  ``$config['rewrite_short_tags']`` now has no effect when using PHP 5.4 as ``<?=`` will always be available.
 	 -  Changed method ``config()`` to return whatever ``CI_Config::load()`` returns instead of always being void.
-	 -  Removed method ``initialize()`` and moved its logic to the constructor.
    -  :doc:`Input Library <libraries/input>` changes include:
 	 -  Added ``method()`` to retrieve ``$_SERVER['REQUEST_METHOD']``.
 	 -  Added support for arrays and network addresses (e.g. 192.168.1.1/24) for use with the *proxy_ips* setting.
diff --git a/user_guide_src/source/database/forge.rst b/user_guide_src/source/database/forge.rst
index bf17e2918..1d6b847b4 100644
--- a/user_guide_src/source/database/forge.rst
+++ b/user_guide_src/source/database/forge.rst
@@ -193,13 +193,15 @@ into the definition
 Dropping a table
 ================
 
-Executes a DROP TABLE sql
+Execute a DROP TABLE statement and optionally add an IF EXISTS clause.
 
 ::
 
+	// Produces: DROP TABLE table_name
 	$this->dbforge->drop_table('table_name');
-	// gives DROP TABLE IF EXISTS  table_name
 
+	// Produces: DROP TABLE IF EXISTS table_name
+	$this->dbforge->drop_table('table_name');
 
 Renaming a table
 ================
@@ -231,14 +233,6 @@ number of additional fields.
 	$this->dbforge->add_column('table_name', $fields); 
 	// gives ALTER TABLE table_name ADD preferences TEXT
 
-An optional third parameter can be used to specify which existing column
-to add the new column after.
-
-::
-
-	$this->dbforge->add_column('table_name', $fields, 'after_field');
-
-
 $this->dbforge->drop_column()
 ==============================
 
diff --git a/user_guide_src/source/general/common_functions.rst b/user_guide_src/source/general/common_functions.rst
index f3d48ac91..7f327f00b 100644
--- a/user_guide_src/source/general/common_functions.rst
+++ b/user_guide_src/source/general/common_functions.rst
@@ -46,10 +46,14 @@ recommended on platforms where this information may be unreliable.
 config_item('item_key')
 =======================
 
-The :doc:`Config library <../libraries/config>` is the preferred way of
-accessing configuration information, however config_item() can be used
-to retrieve single keys. See Config library documentation for more
-information.
+The :doc:`Config Library <../libraries/config>` is the preferred way of
+accessing configuration information, however ``config_item()`` can be used
+to retrieve single keys. See :doc:`Config Library <../libraries/config>`
+documentation for more information.
+
+.. important:: This function only returns values set in your configuration
+	files. It does not take into account config values that are
+	dynamically set at runtime.
 
 show_error('message'), show_404('page'), log_message('level', 'message')
 ========================================================================
diff --git a/user_guide_src/source/general/controllers.rst b/user_guide_src/source/general/controllers.rst
index 6e5079419..150d2269c 100644
--- a/user_guide_src/source/general/controllers.rst
+++ b/user_guide_src/source/general/controllers.rst
@@ -67,21 +67,21 @@ This is **not** valid::
 	?>
 
 Also, always make sure your controller extends the parent controller
-class so that it can inherit all its functions.
+class so that it can inherit all its methods.
 
-Functions
-=========
+Methods
+=======
 
-In the above example the function name is index(). The "index" function
+In the above example the method name is ``index()``. The "index" method
 is always loaded by default if the **second segment** of the URI is
 empty. Another way to show your "Hello World" message would be this::
 
 	example.com/index.php/blog/index/
 
-**The second segment of the URI determines which function in the
+**The second segment of the URI determines which method in the
 controller gets called.**
 
-Let's try it. Add a new function to your controller::
+Let's try it. Add a new method to your controller::
 
 	<?php
 	class Blog extends CI_Controller {
@@ -98,37 +98,37 @@ Let's try it. Add a new function to your controller::
 	}
 	?>
 
-Now load the following URL to see the comment function::
+Now load the following URL to see the comment method::
 
 	example.com/index.php/blog/comments/
 
 You should see your new message.
 
-Passing URI Segments to your Functions
-======================================
+Passing URI Segments to your methods
+====================================
 
 If your URI contains more then two segments they will be passed to your
-function as parameters.
+method as parameters.
 
 For example, lets say you have a URI like this::
 
 	example.com/index.php/products/shoes/sandals/123
 
-Your function will be passed URI segments 3 and 4 ("sandals" and "123")::
+Your method will be passed URI segments 3 and 4 ("sandals" and "123")::
 
 	<?php
 	class Products extends CI_Controller {
 
-	    public function shoes($sandals, $id)
-	    {
-	        echo $sandals;
-	        echo $id;
-	    }
+		public function shoes($sandals, $id)
+		{
+			echo $sandals;
+			echo $id;
+		}
 	}
 	?>
 
 .. important:: If you are using the :doc:`URI Routing <routing>`
-	feature, the segments passed to your function will be the re-routed
+	feature, the segments passed to your method will be the re-routed
 	ones.
 
 Defining a Default Controller
@@ -145,53 +145,53 @@ Where Blog is the name of the controller class you want used. If you now
 load your main index.php file without specifying any URI segments you'll
 see your Hello World message by default.
 
-Remapping Function Calls
-========================
+Remapping Method Calls
+======================
 
 As noted above, the second segment of the URI typically determines which
-function in the controller gets called. CodeIgniter permits you to
-override this behavior through the use of the _remap() function::
+method in the controller gets called. CodeIgniter permits you to override
+this behavior through the use of the ``_remap()`` method::
 
 	public function _remap()
 	{
-	    // Some code here...
+		// Some code here...
 	}
 
-.. important:: If your controller contains a function named _remap(),
+.. important:: If your controller contains a method named _remap(),
 	it will **always** get called regardless of what your URI contains. It
-	overrides the normal behavior in which the URI determines which function
-	is called, allowing you to define your own function routing rules.
+	overrides the normal behavior in which the URI determines which method
+	is called, allowing you to define your own method routing rules.
 
-The overridden function call (typically the second segment of the URI)
-will be passed as a parameter to the _remap() function::
+The overridden method call (typically the second segment of the URI) will
+be passed as a parameter to the ``_remap()`` method::
 
 	public function _remap($method)
 	{
-	    if ($method == 'some_method')
-	    {
-	        $this->$method();
-	    }
-	    else
-	    {
-	        $this->default_method();
-	    }
+		if ($method == 'some_method')
+		{
+			$this->$method();
+		}
+		else
+		{
+			$this->default_method();
+		}
 	}
 
-Any extra segments after the method name are passed into _remap() as an
+Any extra segments after the method name are passed into ``_remap()`` as an
 optional second parameter. This array can be used in combination with
-PHP's `call_user_func_array <http://php.net/call_user_func_array>`_
+PHP's `call_user_func_array() <http://php.net/call_user_func_array>`_
 to emulate CodeIgniter's default behavior.
 
 ::
 
 	public function _remap($method, $params = array())
 	{
-	    $method = 'process_'.$method;
-	    if (method_exists($this, $method))
-	    {
-	        return call_user_func_array(array($this, $method), $params);
-	    }
-	    show_404();
+		$method = 'process_'.$method;
+		if (method_exists($this, $method))
+		{
+			return call_user_func_array(array($this, $method), $params);
+		}
+		show_404();
 	}
 
 Processing Output
@@ -199,29 +199,29 @@ Processing Output
 
 CodeIgniter has an output class that takes care of sending your final
 rendered data to the web browser automatically. More information on this
-can be found in the :doc:`Views <views>` and :doc:`Output class <../libraries/output>` pages. In some cases, however, you
-might want to post-process the finalized data in some way and send it to
-the browser yourself. CodeIgniter permits you to add a function named
-_output() to your controller that will receive the finalized output
-data.
+can be found in the :doc:`Views <views>` and :doc:`Output Class
+<../libraries/output>` pages. In some cases, however, you might want to
+post-process the finalized data in some way and send it to the browser
+yourself. CodeIgniter permits you to add a method named ``_output()``
+to your controller that will receive the finalized output data.
 
-.. important:: If your controller contains a function named _output(),
-	it will **always** be called by the output class instead of echoing the
-	finalized data directly. The first parameter of the function will
-	contain the finalized output.
+.. important:: If your controller contains a method named _output(), it
+	will **always** be called by the output class instead of echoing
+	the finalized data directly. The first parameter of the method
+	will contain the finalized output.
 
 Here is an example::
 
 	public function _output($output)
 	{
-	    echo $output;
+		echo $output;
 	}
 
-.. note:: Please note that your _output() function will receive the data in its
+.. note:: Please note that your _output() method will receive the data in its
 	finalized state. Benchmark and memory usage data will be rendered, cache
 	files written (if you have caching enabled), and headers will be sent
 	(if you use that :doc:`feature <../libraries/output>`) before it is
-	handed off to the _output() function.
+	handed off to the _output() method.
 	To have your controller's output cached properly, its _output() method
 	can use::
 
@@ -236,23 +236,27 @@ Here is an example::
 	output *before* any of the final processing is done, please see the
 	available methods in the :doc:`Output Class <../libraries/output>`.
 
-Private Functions
-=================
+Private methods
+===============
 
-In some cases you may want certain functions hidden from public access.
-To make a function private, simply add an underscore as the name prefix
-and it will not be served via a URL request. For example, if you were to
-have a function like this::
+In some cases you may want certain methods hidden from public access.
+In order to achieve this, simply declare the method as being private
+or protected and it will not be served via a URL request. For example,
+if you were to have a method like this::
 
 	private function _utility()
 	{
-	  // some code
+		// some code
 	}
 
 Trying to access it via the URL, like this, will not work::
 
 	example.com/index.php/blog/_utility/
 
+.. note:: Prefixing method names with an underscore will also prevent
+	them from being called. This is a legacy feature that is left
+	for backwards-compatibility.
+
 Organizing Your Controllers into Sub-folders
 ============================================
 
@@ -297,11 +301,11 @@ manually call it.
 	<?php
 	class Blog extends CI_Controller {
 
-	       public function __construct()
-	       {
-	            parent::__construct();
-	            // Your own constructor code
-	       }
+		public function __construct()
+		{
+			parent::__construct();
+			// Your own constructor code
+		}
 	}
 	?>
 
@@ -309,16 +313,22 @@ Constructors are useful if you need to set some default values, or run a
 default process when your class is instantiated. Constructors can't
 return a value, but they can do some default work.
 
-Reserved Function Names
-=======================
+Reserved method names
+=====================
 
 Since your controller classes will extend the main application
-controller you must be careful not to name your functions identically to
+controller you must be careful not to name your methods identically to
 the ones used by that class, otherwise your local functions will
 override them. See :doc:`Reserved Names <reserved_names>` for a full
 list.
 
+.. important:: You should also never have a method named identically
+	to its class name. If you do, and there is no __construct()
+	method in the same class, then your e.g. Index::index() method
+	will be executed as a class constructor! This is a PHP4
+	backwards-compatibility feature.
+
 That's it!
 ==========
 
-That, in a nutshell, is all there is to know about controllers.
+That, in a nutshell, is all there is to know about controllers.
\ No newline at end of file
diff --git a/user_guide_src/source/installation/upgrade_300.rst b/user_guide_src/source/installation/upgrade_300.rst
index fd5eea478..4e0b952d5 100644
--- a/user_guide_src/source/installation/upgrade_300.rst
+++ b/user_guide_src/source/installation/upgrade_300.rst
@@ -93,9 +93,31 @@ Step 8: Check the calls to Array Helper's element() and elements() functions
 The default return value of these functions, when the required elements
 don't exist, has been changed from FALSE to NULL.
 
-**********************************************************
-Step 9: Change usage of Email library with multiple emails
-**********************************************************
+************************************************************
+Step 9: Update usage of Database Forge's drop_table() method
+************************************************************
+
+Up until now, ``drop_table()`` added an IF EXISTS clause by default or it didn't work
+at all with some drivers. In CodeIgniter 3.0, the IF EXISTS condition is no longer added
+by deafault and has an optional second parameter that allows that instead and is set to
+FALSE by default.
+
+If your application relies on IF EXISTS, you'll have to change its usage.
+
+::
+
+	// Now produces just DROP TABLE `table_name`
+	$this->dbforge->drop_table('table_name');
+
+	// Produces DROP TABLE IF EXISTS `table_name`
+	$this->dbforge->drop_table('table_name', TRUE);
+
+.. note:: The given example users MySQL-specific syntax, but it should work across
+	all drivers with the exception of ODBC.
+
+***********************************************************
+Step 10: Change usage of Email library with multiple emails
+***********************************************************
 
 The :doc:`Email library <../libraries/email>` will automatically clear the
 set parameters after successfully sending emails. To override this behaviour,
@@ -110,7 +132,7 @@ pass FALSE as the first parameter in the ``send()`` method:
 
 
 ****************************************************************
-Step 10: Remove usage of (previously) deprecated functionalities
+Step 11: Remove usage of (previously) deprecated functionalities
 ****************************************************************
 
 In addition to the ``$autoload['core']`` configuration setting, there's a number of other functionalities
diff --git a/user_guide_src/source/libraries/form_validation.rst b/user_guide_src/source/libraries/form_validation.rst
index c010eb578..a3a35b499 100644
--- a/user_guide_src/source/libraries/form_validation.rst
+++ b/user_guide_src/source/libraries/form_validation.rst
@@ -910,9 +910,6 @@ Rule                      Parameter  Description
 	to two parameters, where at least one is required (to pass
 	the field data).
 
-.. note:: When using the **matches** rule, the form item specified
-	to compare against must already be defined.
-
 ******************
 Prepping Reference
 ******************