Merge upstream branch

16 files changed, 3101 insertions, 440 deletions

diff --git a/system/database/drivers/pdo/pdo_driver.php b/system/database/drivers/pdo/pdo_driver.php
index 89e69676d..0ffe3bc13 100644
--- a/system/database/drivers/pdo/pdo_driver.php
+++ b/system/database/drivers/pdo/pdo_driver.php
@@ -42,145 +42,62 @@ class CI_DB_pdo_driver extends CI_DB {
 
 	public $dbdriver = 'pdo';
 
-	// the character used to excape - not necessary for PDO
-	protected $_escape_char = '';
+	// The character used to escaping
+	protected $_escape_char = '"';
 
-	// clause and character used for LIKE escape sequences
-	protected $_like_escape_str = " ESCAPE '%s' ";
-	protected $_like_escape_chr = '!';
-
-	/**
-	 * The syntax to count rows is slightly different across different
-	 * database engines, so this string appears in each driver and is
-	 * used for the count_all() and count_all_results() functions.
-	 */
-	protected $_count_string = 'SELECT COUNT(*) AS ';
 	protected $_random_keyword;
 
-	// need to track the pdo driver and options
-	public $pdodriver;
+	public $trans_enabled = FALSE;
+
+	// need to track the PDO options
 	public $options = array();
 
+	/**
+	 * Constructor
+	 *
+	 * Validates the DSN string and/or detects the subdriver
+	 *
+	 * @param	array
+	 * @return	void
+	 */
 	public function __construct($params)
 	{
 		parent::__construct($params);
 
-		if (preg_match('/([^;]+):/', $this->dsn, $match) && count($match) == 2)
+		if (preg_match('/([^;]+):/', $this->dsn, $match) && count($match) === 2)
 		{
 			// If there is a minimum valid dsn string pattern found, we're done
 			// This is for general PDO users, who tend to have a full DSN string.
-			$this->pdodriver = end($match);
+			$this->subdriver = $match[1];
+			return;
 		}
-		else
+		// Legacy support for DSN specified in the hostname field
+		elseif (preg_match('/([^;]+):/', $this->hostname, $match) && count($match) === 2)
 		{
-			// Try to build a complete DSN string from params
-			$this->_connect_string($params);
+			$this->dsn = $this->hostname;
+			$this->hostname = NULL;
+			$this->subdriver = $match[1];
+			return;
 		}
-
-		// clause and character used for LIKE escape sequences
-		// this one depends on the driver being used
-		if ($this->pdodriver == 'mysql')
+		elseif (in_array($this->subdriver, array('mssql', 'sybase'), TRUE))
 		{
-			$this->_escape_char = '`';
-			$this->_like_escape_str = '';
-			$this->_like_escape_chr = '';
+			$this->subdriver = 'dblib';
 		}
-		elseif ($this->pdodriver == 'odbc')
+		elseif ($this->subdriver === '4D')
 		{
-			$this->_like_escape_str = " {escape '%s'} ";
+			$this->subdriver = '4d';
 		}
-		elseif ( ! in_array($this->pdodriver, array('sqlsrv', 'mssql', 'dblib', 'sybase')))
+		elseif ( ! in_array($this->subdriver, array('4d', 'cubrid', 'dblib', 'firebird', 'ibm', 'informix', 'mysql', 'oci', 'odbc', 'sqlite', 'sqlsrv'), TRUE))
 		{
-			$this->_escape_char = '"';
-		}
-
-		$this->trans_enabled = FALSE;
-		$this->_random_keyword = ' RND('.time().')'; // database specific random keyword
-	}
+			log_message('error', 'PDO: Invalid or non-existent subdriver');
 
-	/**
-	 * Connection String
-	 *
-	 * @param	array
-	 * @return	void
-	 */
-	protected function _connect_string($params)
-	{
-		if (strpos($this->hostname, ':'))
-		{
-			// hostname generally would have this prototype
-			// $db['hostname'] = 'pdodriver:host(/Server(/DSN))=hostname(/DSN);';
-			// We need to get the prefix (pdodriver used by PDO).
-			$dsnarray = explode(':', $this->hostname);
-			$this->pdodriver = $dsnarray[0];
-
-			// End dsn with a semicolon for extra backward compability
-			// if database property was not empty.
-			if ( ! empty($this->database))
+			if ($this->db_debug)
 			{
-				$this->dsn .= rtrim($this->hostname, ';').';';
+				show_error('Invalid or non-existent PDO subdriver');
 			}
 		}
-		else
-		{
-			// Invalid DSN, display an error
-			if ( ! array_key_exists('pdodriver', $params))
-			{
-				show_error('Invalid DB Connection String for PDO');
-			}
-
-			// Assuming that the following DSN string format is used:
-			// $dsn = 'pdo://username:password@hostname:port/database?pdodriver=pgsql';
-			$this->dsn = $this->pdodriver.':';
-
-			// Add hostname to the DSN for databases that need it
-			if ( ! empty($this->hostname)
-				&& strpos($this->hostname, ':') === FALSE
-				&& in_array($this->pdodriver, array('informix', 'mysql', 'pgsql', 'sybase', 'mssql', 'dblib', 'cubrid')))
-			{
-			    $this->dsn .= 'host='.$this->hostname.';';
-			}
 
-			// Add a port to the DSN for databases that can use it
-			if ( ! empty($this->port) && in_array($this->pdodriver, array('informix', 'mysql', 'pgsql', 'ibm', 'cubrid')))
-			{
-			    $this->dsn .= 'port='.$this->port.';';
-			}
-		}
-
-		// Add the database name to the DSN, if needed
-	    if (stripos($this->dsn, 'dbname') === FALSE
-	       && in_array($this->pdodriver, array('4D', 'pgsql', 'mysql', 'firebird', 'sybase', 'mssql', 'dblib', 'cubrid')))
-	    {
-	        $this->dsn .= 'dbname='.$this->database.';';
-	    }
-	    elseif (stripos($this->dsn, 'database') === FALSE && in_array($this->pdodriver, array('ibm', 'sqlsrv')))
-	    {
-	    	if (stripos($this->dsn, 'dsn') === FALSE)
-	    	{
-		        $this->dsn .= 'database='.$this->database.';';
-	    	}
-	    }
-	    elseif ($this->pdodriver === 'sqlite' && $this->dsn === 'sqlite:')
-	    {
-	        if ($this->database !== ':memory')
-	        {
-	            if ( ! file_exists($this->database))
-	            {
-	                show_error('Invalid DB Connection string for PDO SQLite');
-	            }
-
-	            $this->dsn .= (strpos($this->database, DIRECTORY_SEPARATOR) !== 0) ? DIRECTORY_SEPARATOR : '';
-	        }
-
-	        $this->dsn .= $this->database;
-	    }
-
-	    // Add charset to the DSN, if needed
-	    if ( ! empty($this->char_set) && in_array($this->pdodriver, array('4D', 'mysql', 'sybase', 'mssql', 'dblib', 'oci')))
-	    {
-	        $this->dsn .= 'charset='.$this->char_set.';';
-	    }
+		$this->dsn = NULL;
 	}
 
 	// --------------------------------------------------------------------
@@ -188,11 +105,27 @@ class CI_DB_pdo_driver extends CI_DB {
 	/**
 	 * Non-persistent database connection
 	 *
+	 * @param	bool
 	 * @return	object
 	 */
-	public function db_connect()
+	public function db_connect($persistent = FALSE)
 	{
-		return $this->_pdo_connect();
+		$this->options[PDO::ATTR_PERSISTENT] = $persistent;
+
+		// Connecting...
+		try
+		{
+			return @new PDO($this->dsn, $this->username, $this->password, $this->options);
+		}
+		catch (PDOException $e)
+		{
+			if ($this->db_debug && empty($this->failover))
+			{
+				$this->display_error($e->getMessage(), '', TRUE);
+			}
+
+			return FALSE;
+		}
 	}
 
 	// --------------------------------------------------------------------
@@ -204,66 +137,37 @@ class CI_DB_pdo_driver extends CI_DB {
 	 */
 	public function db_pconnect()
 	{
-		return $this->_pdo_connect(TRUE);
+		return $this->db_connect(TRUE);
 	}
 
 	// --------------------------------------------------------------------
 
 	/**
-	 * PDO connection
+	 * Database version number
 	 *
-	 * @param	bool
-	 * @return	object
+	 * @return	string
 	 */
-	protected function _pdo_connect($persistent = FALSE)
+	public function version()
 	{
-		$this->options[PDO::ATTR_ERRMODE] = PDO::ERRMODE_SILENT;
-		$persistent === FALSE OR $this->options[PDO::ATTR_PERSISTENT] = TRUE;
-
-		/* Prior to PHP 5.3.6, even if the charset was supplied in the DSN
-		 * on connect - it was ignored. This is a work-around for the issue.
-		 *
-		 * Reference: http://www.php.net/manual/en/ref.pdo-mysql.connection.php
-		 */
-		if ($this->pdodriver === 'mysql' && ! is_php('5.3.6') && ! empty($this->char_set))
+		if (isset($this->data_cache['version']))
 		{
-			$this->options[PDO::MYSQL_ATTR_INIT_COMMAND] = 'SET NAMES '.$this->char_set
-					.( ! empty($this->db_collat) ? " COLLATE '".$this->dbcollat."'" : '');
+			return $this->data_cache['version'];
 		}
 
-		// Connecting...
+		// Not all subdrivers support the getAttribute() method
 		try
 		{
-			return new PDO($this->dsn, $this->username, $this->password, $this->options);
+			return $this->data_cache['version'] = $this->conn_id->getAttribute(PDO::ATTR_SERVER_VERSION);
 		}
 		catch (PDOException $e)
 		{
-			if ($this->db_debug && empty($this->failover))
-			{
-				$this->display_error($e->getMessage(), '', TRUE);
-			}
-
-			return FALSE;
+			return parent::version();
 		}
 	}
 
 	// --------------------------------------------------------------------
 
 	/**
-	 * Database version number
-	 *
-	 * @return	string
-	 */
-	public function version()
-	{
-		return isset($this->data_cache['version'])
-			? $this->data_cache['version']
-			: $this->data_cache['version'] = $this->conn_id->getAttribute(PDO::ATTR_SERVER_VERSION);
-	}
-
-	// --------------------------------------------------------------------
-
-	/**
 	 * Execute the query
 	 *
 	 * @param	string	an SQL query
@@ -358,7 +262,7 @@ class CI_DB_pdo_driver extends CI_DB {
 		$str = $this->conn_id->quote($str);
 
 		// If there are duplicated quotes, trim them away
-		if (strpos($str, "'") === 0)
+		if ($str[0] === "'")
 		{
 			$str = substr($str, 1, -1);
 		}
@@ -396,101 +300,12 @@ class CI_DB_pdo_driver extends CI_DB {
 	 */
 	public function insert_id($name = NULL)
 	{
-		if ($this->pdodriver === 'pgsql' && $name === NULL && $this->version() >= '8.1')
-		{
-			$query = $this->query('SELECT LASTVAL() AS ins_id');
-			$query = $query->row();
-			return $query->ins_id;
-		}
-
 		return $this->conn_id->lastInsertId($name);
 	}
 
 	// --------------------------------------------------------------------
 
 	/**
-	 * "Count All" query
-	 *
-	 * Generates a platform-specific query string that counts all records in
-	 * the specified database
-	 *
-	 * @param	string
-	 * @return	string
-	 */
-	public function count_all($table = '')
-	{
-		if ($table == '')
-		{
-			return 0;
-		}
-
-		$sql = $this->_count_string.$this->protect_identifiers('numrows').' FROM '.$this->protect_identifiers($table, TRUE, NULL, FALSE);
-		$query = $this->query($sql);
-
-		if ($query->num_rows() == 0)
-		{
-			return 0;
-		}
-
-		$row = $query->row();
-		$this->_reset_select();
-
-		return (int) $row->numrows;
-	}
-
-	// --------------------------------------------------------------------
-
-	/**
-	 * Show table query
-	 *
-	 * Generates a platform-specific query string so that the table names can be fetched
-	 *
-	 * @param	bool
-	 * @return	string
-	 */
-	protected function _list_tables($prefix_limit = FALSE)
-	{
-		if ($this->pdodriver == 'pgsql')
-		{
-			// Analog function to show all tables in postgre
-			$sql = "SELECT * FROM information_schema.tables WHERE table_schema = 'public'";
-		}
-		elseif ($this->pdodriver == 'sqlite')
-		{
-			// Analog function to show all tables in sqlite
-			$sql = "SELECT name FROM sqlite_master WHERE type='table' AND name NOT LIKE 'sqlite_%'";
-		}
-		else
-		{
-			$sql = 'SHOW TABLES FROM '.$this->escape_identifiers($this->database);
-		}
-
-		if ($prefix_limit !== FALSE AND $this->dbprefix != '')
-		{
-			return FALSE;
-		}
-
-		return $sql;
-	}
-
-	// --------------------------------------------------------------------
-
-	/**
-	 * Show column query
-	 *
-	 * Generates a platform-specific query string so that the column names can be fetched
-	 *
-	 * @param	string	the table name
-	 * @return	string
-	 */
-	protected function _list_columns($table = '')
-	{
-		return 'SHOW COLUMNS FROM '.$this->escape_identifiers($table);
-	}
-
-	// --------------------------------------------------------------------
-
-	/**
 	 * Field data query
 	 *
 	 * Generates a platform-specific query so that the column data can be retrieved
@@ -500,23 +315,7 @@ class CI_DB_pdo_driver extends CI_DB {
 	 */
 	protected function _field_data($table)
 	{
-		if ($this->pdodriver == 'mysql' or $this->pdodriver == 'pgsql')
-		{
-			// Analog function for mysql and postgre
-			return 'SELECT * FROM '.$this->escape_identifiers($table).' LIMIT 1';
-		}
-		elseif ($this->pdodriver == 'oci')
-		{
-			// Analog function for oci
-			return 'SELECT * FROM '.$this->escape_identifiers($table).' WHERE ROWNUM <= 1';
-		}
-		elseif ($this->pdodriver == 'sqlite')
-		{
-			// Analog function for sqlite
-			return 'PRAGMA table_info('.$this->escape_identifiers($table).')';
-		}
-
-		return 'SELECT TOP 1 FROM '.$this->escape_identifiers($table);
+		return 'SELECT TOP 1 * FROM '.$this->protect_identifiers($table);
 	}
 
 	// --------------------------------------------------------------------
@@ -551,27 +350,6 @@ class CI_DB_pdo_driver extends CI_DB {
 	// --------------------------------------------------------------------
 
 	/**
-	 * From Tables
-	 *
-	 * This function implicitly groups FROM tables so there is no confusion
-	 * about operator precedence in harmony with SQL standards
-	 *
-	 * @param	array
-	 * @return	string
-	 */
-	protected function _from_tables($tables)
-	{
-		if ( ! is_array($tables))
-		{
-			$tables = array($tables);
-		}
-
-		return (count($tables) === 1) ? $tables[0] : '('.implode(', ', $tables).')';
-	}
-
-	// --------------------------------------------------------------------
-
-	/**
 	 * Update_Batch statement
 	 *
 	 * Generates a platform-specific batch update string from the supplied data
@@ -583,8 +361,8 @@ class CI_DB_pdo_driver extends CI_DB {
 	 */
 	protected function _update_batch($table, $values, $index, $where = NULL)
 	{
-		$ids   = array();
-		$where = ($where != '' && count($where) >=1) ? implode(" ", $where).' AND ' : '';
+		$ids = array();
+		$where = ($where !== '' && count($where) >=1) ? implode(' ', $where).' AND ' : '';
 
 		foreach ($values as $key => $val)
 		{
@@ -592,7 +370,7 @@ class CI_DB_pdo_driver extends CI_DB {
 
 			foreach (array_keys($val) as $field)
 			{
-				if ($field != $index)
+				if ($field !== $index)
 				{
 					$final[$field][] =  'WHEN '.$index.' = '.$val[$index].' THEN '.$val[$field];
 				}
@@ -635,49 +413,7 @@ class CI_DB_pdo_driver extends CI_DB {
 	 */
 	protected function _truncate($table)
 	{
-		return 'DELETE FROM '.$table;
-	}
-
-	// --------------------------------------------------------------------
-
-	/**
-	 * Limit string
-	 *
-	 * Generates a platform-specific LIMIT clause
-	 *
-	 * @param	string	the sql query string
-	 * @param	int	the number of rows to limit the query to
-	 * @param	int	the offset value
-	 * @return	string
-	 */
-	protected function _limit($sql, $limit, $offset)
-	{
-		if ($this->pdodriver == 'cubrid' OR $this->pdodriver == 'sqlite')
-		{
-			$offset = ($offset == 0) ? '' : $offset.', ';
-
-			return $sql.'LIMIT '.$offset.$limit;
-		}
-		else
-		{
-			$sql .= 'LIMIT '.$limit;
-			$sql .= ($offset > 0) ? ' OFFSET '.$offset : '';
-
-			return $sql;
-		}
-	}
-
-	// --------------------------------------------------------------------
-
-	/**
-	 * Close DB Connection
-	 *
-	 * @param	object
-	 * @return	void
-	 */
-	protected function _close($conn_id)
-	{
-		$this->conn_id = NULL;
+		return 'TRUNCATE TABLE '.$table;
 	}
 
 }
diff --git a/system/database/drivers/pdo/pdo_forge.php b/system/database/drivers/pdo/pdo_forge.php
index ca8657a0f..34a6ee44e 100644
--- a/system/database/drivers/pdo/pdo_forge.php
+++ b/system/database/drivers/pdo/pdo_forge.php
@@ -34,7 +34,6 @@
  */
 class CI_DB_pdo_forge extends CI_DB_forge {
 
-	protected $_drop_database	= 'DROP DATABASE %s';
 	protected $_drop_table		= 'DROP TABLE %s';
 
 	/**
@@ -66,46 +65,38 @@ class CI_DB_pdo_forge extends CI_DB_forge {
 			// entered the field information, so we'll simply add it to the list
 			if (is_numeric($field))
 			{
-				$sql .= "\n\t$attributes";
+				$sql .= "\n\t".$attributes;
 			}
 			else
 			{
 				$attributes = array_change_key_case($attributes, CASE_UPPER);
-				$numeric    = array('SERIAL', 'INTEGER');
+				$numeric = array('SERIAL', 'INTEGER');
 
-				$sql .= "\n\t".$this->db->protect_identifiers($field);
+				$sql .= "\n\t".$this->db->escape_identifiers($field).' '.$attributes['TYPE'];
 
-				$sql .=  ' '.$attributes['TYPE'];
-
-				if (array_key_exists('CONSTRAINT', $attributes))
+				if ( ! empty($attributes['CONSTRAINT']))
 				{
 					// Exception for Postgre numeric which not too happy with constraint within those type
-					if ( ! ($this->db->pdodriver == 'pgsql' && in_array($attributes['TYPE'], $numeric)))
+					if ( ! ($this->db->subdriver === 'pgsql' && in_array($attributes['TYPE'], $numeric)))
 					{
 						$sql .= '('.$attributes['CONSTRAINT'].')';
 					}
 				}
 
-				if (array_key_exists('UNSIGNED', $attributes) && $attributes['UNSIGNED'] === TRUE)
+				if ( ! empty($attributes['UNSIGNED']) && $attributes['UNSIGNED'] === TRUE)
 				{
 					$sql .= ' UNSIGNED';
 				}
 
-				if (array_key_exists('DEFAULT', $attributes))
+				if (isset($attributes['DEFAULT']))
 				{
-					$sql .= ' DEFAULT \''.$attributes['DEFAULT'].'\'';
+					$sql .= " DEFAULT '".$attributes['DEFAULT']."'";
 				}
 
-				if (array_key_exists('NULL', $attributes) && $attributes['NULL'] === TRUE)
-				{
-					$sql .= ' NULL';
-				}
-				else
-				{
-					$sql .= ' NOT NULL';
-				}
+				$sql .= ( ! empty($attributes['NULL']) && $attributes['NULL'] === TRUE)
+					? ' NULL' : ' NOT NULL';
 
-				if (array_key_exists('AUTO_INCREMENT', $attributes) && $attributes['AUTO_INCREMENT'] === TRUE)
+				if ( ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE)
 				{
 					$sql .= ' AUTO_INCREMENT';
 				}
@@ -120,30 +111,22 @@ class CI_DB_pdo_forge extends CI_DB_forge {
 
 		if (count($primary_keys) > 0)
 		{
-			$primary_keys = $this->db->protect_identifiers($primary_keys);
-			$sql .= ",\n\tPRIMARY KEY (" . implode(', ', $primary_keys) . ")";
+			$sql .= ",\n\tPRIMARY KEY (".implode(', ', $this->db->escape_identifiers($primary_keys)).')';
 		}
 
 		if (is_array($keys) && count($keys) > 0)
 		{
 			foreach ($keys as $key)
 			{
-				if (is_array($key))
-				{
-					$key = $this->db->protect_identifiers($key);
-				}
-				else
-				{
-					$key = array($this->db->protect_identifiers($key));
-				}
+				$key = is_array($key)
+					? $this->db->escape_identifiers($key)
+					: array($this->db->escape_identifiers($key));
 
-				$sql .= ",\n\tFOREIGN KEY (" . implode(', ', $key) . ")";
+				$sql .= ",\n\tFOREIGN KEY (".implode(', ', $key).')';
 			}
 		}
 
-		$sql .= "\n)";
-
-		return $sql;
+		return $sql."\n)";
 	}
 
 	// --------------------------------------------------------------------
@@ -165,37 +148,18 @@ class CI_DB_pdo_forge extends CI_DB_forge {
 	 */
 	protected function _alter_table($alter_type, $table, $column_name, $column_definition = '', $default_value = '', $null = '', $after_field = '')
 	{
-		$sql = 'ALTER TABLE `'.$this->db->protect_identifiers($table).'` '.$alter_type.' '.$this->db->protect_identifiers($column_name);
+		$sql = 'ALTER TABLE '.$this->db->escape_identifiers($table).' '.$alter_type.' '.$this->db->escape_identifiers($column_name);
 
 		// DROP has everything it needs now.
-		if ($alter_type == 'DROP')
+		if ($alter_type === 'DROP')
 		{
 			return $sql;
 		}
 
-		$sql .= " $column_definition";
-
-		if ($default_value != '')
-		{
-			$sql .= " DEFAULT \"$default_value\"";
-		}
-
-		if ($null === NULL)
-		{
-			$sql .= ' NULL';
-		}
-		else
-		{
-			$sql .= ' NOT NULL';
-		}
-
-		if ($after_field != '')
-		{
-			return $sql.' AFTER '.$this->db->protect_identifiers($after_field);
-		}
-
-		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) : '');
 	}
 
 }
diff --git a/system/database/drivers/pdo/pdo_result.php b/system/database/drivers/pdo/pdo_result.php
index 0b8937cc5..444406986 100644
--- a/system/database/drivers/pdo/pdo_result.php
+++ b/system/database/drivers/pdo/pdo_result.php
@@ -21,7 +21,7 @@
  * @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
+ * @since		Version 1.0
  * @filesource
  */
 
@@ -33,72 +33,35 @@
  * @category	Database
  * @author		EllisLab Dev Team
  * @link		http://codeigniter.com/user_guide/database/
+ * @since	2.1
  */
 class CI_DB_pdo_result extends CI_DB_result {
 
 	/**
-	 * @var bool  Hold the flag whether a result handler already fetched before
-	 */
-	protected $is_fetched = FALSE;
-
-	/**
-	 * @var mixed Hold the fetched assoc array of a result handler
-	 */
-	protected $result_assoc;
-
-	/**
 	 * Number of rows in the result set
 	 *
 	 * @return	int
 	 */
 	public function num_rows()
 	{
-		if (empty($this->result_id) OR ! is_object($this->result_id))
+		if (is_int($this->num_rows))
 		{
-			// invalid result handler
-			return 0;
+			return $this->num_rows;
 		}
-		elseif (($num_rows = $this->result_id->rowCount()) && $num_rows > 0)
+		elseif (count($this->result_array) > 0)
 		{
-			// If rowCount return something, we're done.
-			return $num_rows;
+			return $this->num_rows = count($this->result_array);
 		}
-
-		// Fetch the result, instead perform another extra query
-		return ($this->is_fetched && is_array($this->result_assoc)) ? count($this->result_assoc) : count($this->result_assoc());
-	}
-
-	/**
-	 * Fetch the result handler
-	 *
-	 * @return	mixed
-	 */
-	public function result_assoc()
-	{
-		// If the result already fetched before, use that one
-		if (count($this->result_array) > 0 OR $this->is_fetched)
+		elseif (count($this->result_object) > 0)
 		{
-			return $this->result_array();
+			return $this->num_rows = count($this->result_object);
 		}
-
-		// Define the output
-		$output = array('assoc', 'object');
-
-		// Initial value
-		$this->result_assoc = array() and $this->result_object = array();
-
-		// Fetch the result
-		while ($row = $this->_fetch_assoc())
+		elseif (($num_rows = $this->result_id->rowCount()) > 0)
 		{
-			$this->result_assoc[] = $row;
-			$this->result_object[] = (object) $row;
+			return $this->num_rows = $num_rows;
 		}
 
-		// Save this as buffer and marked the fetch flag
-		$this->result_array = $this->result_assoc;
-		$this->is_fetched = TRUE;
-
-		return $this->result_assoc;
+		return $this->num_rows = count($this->result_array());
 	}
 
 	// --------------------------------------------------------------------
@@ -124,12 +87,14 @@ class CI_DB_pdo_result extends CI_DB_result {
 	 */
 	public function list_fields()
 	{
-		if ($this->db->db_debug)
+		$field_names = array();
+		for ($i = 0, $c = $this->num_fields(); $i < $c; $i++)
 		{
-			return $this->db->display_error('db_unsuported_feature');
+			$field_names[$i] = @$this->result_id->getColumnMeta();
+			$field_names[$i] = $field_names[$i]['name'];
 		}
 
-		return FALSE;
+		return $field_names;
 	}
 
 	// --------------------------------------------------------------------
@@ -240,11 +205,12 @@ class CI_DB_pdo_result extends CI_DB_result {
 	 *
 	 * Returns the result set as an object
 	 *
+	 * @param	string
 	 * @return	object
 	 */
-	protected function _fetch_object()
+	protected function _fetch_object($class_name = 'stdClass')
 	{
-		return $this->result_id->fetch(PDO::FETCH_OBJ);
+		return $this->result_id->fetchObject($class_name);
 	}
 
 }
diff --git a/system/database/drivers/pdo/subdrivers/index.html b/system/database/drivers/pdo/subdrivers/index.html
new file mode 100644
index 000000000..c942a79ce
--- /dev/null
+++ b/system/database/drivers/pdo/subdrivers/index.html
@@ -0,0 +1,10 @@
+<html>
+<head>
+	<title>403 Forbidden</title>
+</head>
+<body>
+
+<p>Directory access is forbidden.</p>
+
+</body>
+</html>
\ No newline at end of file
diff --git a/system/database/drivers/pdo/subdrivers/pdo_4d_driver.php b/system/database/drivers/pdo/subdrivers/pdo_4d_driver.php
new file mode 100644
index 000000000..e287f5c63
--- /dev/null
+++ b/system/database/drivers/pdo/subdrivers/pdo_4d_driver.php
@@ -0,0 +1,223 @@
+<?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 3.0.0
+ * @filesource
+ */
+
+/**
+ * PDO 4D Database Adapter Class
+ *
+ * Note: _DB is an extender class that the app controller
+ * creates dynamically based on whether the query builder
+ * class is being used or not.
+ *
+ * @package		CodeIgniter
+ * @subpackage	Drivers
+ * @category	Database
+ * @author		EllisLab Dev Team
+ * @link		http://codeigniter.com/user_guide/database/
+ */
+class CI_DB_pdo_4d_driver extends CI_DB_pdo_driver {
+
+	public $subdriver = '4d';
+
+	// The character used for escaping
+	protected $_escape_char = array('[', ']');
+
+	protected $_random_keyword = ' RAND()';
+
+	/**
+	 * Constructor
+	 *
+	 * Builds the DSN if not already set.
+	 *
+	 * @param	array
+	 * @return	void
+	 */
+	public function __construct($params)
+	{
+		parent::__construct($params);
+
+		if (empty($this->dsn))
+		{
+			$this->dsn = '4D:host='.(empty($this->hostname) ? '127.0.0.1' : $this->hostname);
+
+			empty($this->port) OR $this->dsn .= ';port='.$this->port;
+			empty($this->database) OR $this->dsn .= ';dbname='.$this->database;
+			empty($this->char_set) OR $this->dsn .= ';charset='.$this->char_set;
+		}
+		elseif ( ! empty($this->char_set) && strpos($this->dsn, 'charset=', 3) === FALSE)
+		{
+			$this->dsn .= ';charset='.$this->char_set;
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Show table query
+	 *
+	 * Generates a platform-specific query string so that the table names can be fetched
+	 *
+	 * @param	bool
+	 * @return	string
+	 */
+	protected function _list_tables($prefix_limit = FALSE)
+	{
+		$sql = 'SELECT '.$this->escape_identifiers('TABLE_NAME').' FROM '.$this->escape_identifiers('_USER_TABLES');
+
+		if ($prefix_limit === TRUE && $this->dbprefix !== '')
+		{
+			$sql .= ' WHERE '.$this->escape_identifiers('TABLE_NAME')." LIKE '".$this->escape_like_str($this->dbprefix)."%' "
+				.sprintf($this->_like_escape_str, $this->_like_escape_chr);
+		}
+
+		return $sql;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Show column query
+	 *
+	 * Generates a platform-specific query string so that the column names can be fetched
+	 *
+	 * @param	string	the table name
+	 * @return	string
+	 */
+	protected function _list_columns($table = '')
+	{
+		return 'SELECT '.$this->escape_identifiers('COLUMN_NAME').' FROM '.$this->escape_identifiers('_USER_COLUMNS')
+			.' WHERE '.$this->escape_identifiers('TABLE_NAME').' = '.$this->escape($table);
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field data query
+	 *
+	 * Generates a platform-specific query so that the column data can be retrieved
+	 *
+	 * @param	string	the table name
+	 * @return	string
+	 */
+	protected function _field_data($table)
+	{
+		return 'SELECT * FROM '.$this->protect_identifiers($table, TRUE, NULL, FALSE).' LIMIT 1';
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * From Tables
+	 *
+	 * This function implicitly groups FROM tables so there is no confusion
+	 * about operator precedence in harmony with SQL standards
+	 *
+	 * @param	array
+	 * @return	string
+	 */
+	protected function _from_tables($tables)
+	{
+		return is_array($tables) ? implode(', ', $tables) : $tables;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Update statement
+	 *
+	 * Generates a platform-specific update string from the supplied data
+	 *
+	 * @param	string	the table name
+	 * @param	array	the update data
+	 * @param	array	the where clause
+	 * @param	array	the orderby clause (ignored)
+	 * @param	array	the limit clause (ignored)
+	 * @param	array	the like clause
+	 * @return	string
+         */
+	protected function _update($table, $values, $where, $orderby = array(), $limit = FALSE, $like = array())
+	{
+		foreach ($values as $key => $val)
+		{
+			$valstr[] = $key.' = '.$val;
+		}
+
+		$where = empty($where) ? '' : ' WHERE '.implode(' ', $where);
+
+		if ( ! empty($like))
+		{
+			$where .= ($where === '' ? ' WHERE ' : ' AND ').implode(' ', $like);
+		}
+
+		return 'UPDATE '.$table.' SET '.implode(', ', $valstr).$where;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Delete statement
+	 *
+	 * Generates a platform-specific delete string from the supplied data
+	 *
+	 * @param	string	the table name
+	 * @param	array	the where clause
+	 * @param	array	the like clause
+	 * @param	string	the limit clause (ignored)
+	 * @return	string
+	 */
+	protected function _delete($table, $where = array(), $like = array(), $limit = FALSE)
+	{
+		$conditions = array();
+
+		empty($where) OR $conditions[] = implode(' ', $where);
+		empty($like) OR $conditions[] = implode(' ', $like);
+
+		$conditions = (count($conditions) > 0) ? ' WHERE '.implode(' AND ', $conditions) : '';
+
+		return 'DELETE FROM '.$table.$conditions;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Limit string
+	 *
+	 * Generates a platform-specific LIMIT clause
+	 *
+	 * @param	string	the sql query string
+	 * @param	int	the number of rows to limit the query to
+	 * @param	int	the offset value
+	 * @return	string
+	 */
+	protected function _limit($sql, $limit, $offset)
+	{
+		return $sql.' LIMIT '.$limit.($offset ? ' OFFSET '.$offset : '');
+	}
+
+}
+
+/* End of file pdo_4d_driver.php */
+/* Location: ./system/database/drivers/pdo/subdrivers/pdo_4d_driver.php */
\ No newline at end of file
diff --git a/system/database/drivers/pdo/subdrivers/pdo_cubrid_driver.php b/system/database/drivers/pdo/subdrivers/pdo_cubrid_driver.php
new file mode 100644
index 000000000..eb3714783
--- /dev/null
+++ b/system/database/drivers/pdo/subdrivers/pdo_cubrid_driver.php
@@ -0,0 +1,185 @@
+<?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 3.0.0
+ * @filesource
+ */
+
+/**
+ * PDO CUBRID Database Adapter Class
+ *
+ * Note: _DB is an extender class that the app controller
+ * creates dynamically based on whether the query builder
+ * class is being used or not.
+ *
+ * @package		CodeIgniter
+ * @subpackage	Drivers
+ * @category	Database
+ * @author		EllisLab Dev Team
+ * @link		http://codeigniter.com/user_guide/database/
+ */
+class CI_DB_pdo_cubrid_driver extends CI_DB_pdo_driver {
+
+	public $subdriver = 'cubrid';
+
+	protected $_escape_char = '`';
+
+	protected $_random_keyword = ' RAND()';
+
+	/**
+	 * Constructor
+	 *
+	 * Builds the DSN if not already set.
+	 *
+	 * @param	array
+	 * @return	void
+	 */
+	public function __construct($params)
+	{
+		parent::__construct($params);
+
+		if (empty($this->dsn))
+		{
+			$this->dsn = 'cubrid:host='.(empty($this->hostname) ? '127.0.0.1' : $this->hostname);
+
+			empty($this->port) OR $this->dsn .= ';port='.$this->port;
+			empty($this->database) OR $this->dsn .= ';dbname='.$this->database;
+			empty($this->char_set) OR $this->dsn .= ';charset='.$this->char_set;
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Show table query
+	 *
+	 * Generates a platform-specific query string so that the table names can be fetched
+	 *
+	 * @param	bool
+	 * @return	string
+	 */
+	protected function _list_tables($prefix_limit = FALSE)
+	{
+		$sql = 'SHOW TABLES';
+
+		if ($prefix_limit === TRUE && $this->dbprefix !== '')
+		{
+			return $sql." LIKE '".$this->escape_like_str($this->dbprefix)."%'";
+		}
+
+		return $sql;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Show column query
+	 *
+	 * Generates a platform-specific query string so that the column names can be fetched
+	 *
+	 * @param	string	the table name
+	 * @return	string
+	 */
+	protected function _list_columns($table = '')
+	{
+		return 'SHOW COLUMNS FROM '.$this->protect_identifiers($table, TRUE, NULL, FALSE);
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field data query
+	 *
+	 * Generates a platform-specific query so that the column data can be retrieved
+	 *
+	 * @param	string	the table name
+	 * @return	string
+	 */
+	protected function _field_data($table)
+	{
+		return 'SELECT * FROM '.$this->protect_identifiers($table).' LIMIT 1';
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Update_Batch statement
+	 *
+	 * Generates a platform-specific batch update string from the supplied data
+	 *
+	 * @param	string	the table name
+	 * @param	array	the update data
+	 * @param	array	the where clause
+	 * @return	string
+	 */
+	protected function _update_batch($table, $values, $index, $where = NULL)
+	{
+		$ids = array();
+		foreach ($values as $key => $val)
+		{
+			$ids[] = $val[$index];
+
+			foreach (array_keys($val) as $field)
+			{
+				if ($field !== $index)
+				{
+					$final[$field][] =  'WHEN '.$index.' = '.$val[$index].' THEN '.$val[$field];
+				}
+			}
+		}
+
+		$cases = '';
+		foreach ($final as $k => $v)
+		{
+			$cases .= $k." = CASE \n"
+				.implode("\n", $v)."\n"
+				.'ELSE '.$k.' END), ';
+		}
+
+		return 'UPDATE '.$table.' SET '.substr($cases, 0, -2)
+			.' WHERE '.(($where !== '' && count($where) > 0) ? implode(' ', $where).' AND ' : '')
+			.$index.' IN('.implode(',', $ids).')';
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Truncate statement
+	 *
+	 * Generates a platform-specific truncate string from the supplied data
+	 *
+	 * If the database does not support the truncate() command,
+	 * then this method maps to 'DELETE FROM table'
+	 *
+	 * @param	string	the table name
+	 * @return	string
+	 */
+	protected function _truncate($table)
+	{
+		return 'TRUNCATE '.$table;
+	}
+
+}
+
+/* End of file pdo_cubrid_driver.php */
+/* Location: ./system/database/drivers/pdo/subdrivers/pdo_cubrid_driver.php */
\ No newline at end of file
diff --git a/system/database/drivers/pdo/subdrivers/pdo_dblib_driver.php b/system/database/drivers/pdo/subdrivers/pdo_dblib_driver.php
new file mode 100644
index 000000000..7060c9eb9
--- /dev/null
+++ b/system/database/drivers/pdo/subdrivers/pdo_dblib_driver.php
@@ -0,0 +1,265 @@
+<?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 3.0.0
+ * @filesource
+ */
+
+/**
+ * PDO DBLIB Database Adapter Class
+ *
+ * Note: _DB is an extender class that the app controller
+ * creates dynamically based on whether the query builder
+ * class is being used or not.
+ *
+ * @package		CodeIgniter
+ * @subpackage	Drivers
+ * @category	Database
+ * @author		EllisLab Dev Team
+ * @link		http://codeigniter.com/user_guide/database/
+ */
+class CI_DB_pdo_dblib_driver extends CI_DB_pdo_driver {
+
+	public $subdriver = 'dblib';
+
+	protected $_random_keyword = ' NEWID()';
+
+	protected $_quoted_identifier;
+
+	/**
+	 * Constructor
+	 *
+	 * Builds the DSN if not already set.
+	 *
+	 * @param	array
+	 * @return	void
+	 */
+	public function __construct($params)
+	{
+		parent::__construct($params);
+
+		if (empty($this->dsn))
+		{
+			$this->dsn = $params['subdriver'].':host='.(empty($this->hostname) ? '127.0.0.1' : $this->hostname);
+
+			if ( ! empty($this->port))
+			{
+				$this->dsn .= (DIRECTORY_SEPARATOR === '\\' ? ',' : ':').$this->port;
+			}
+
+			empty($this->database) OR $this->dsn .= ';dbname='.$this->database;
+			empty($this->char_set) OR $this->dsn .= ';charset='.$this->char_set;
+			empty($this->appname) OR $this->dsn .= ';appname='.$this->appname;
+		}
+		else
+		{
+			if ( ! empty($this->char_set) && strpos($this->dsn, 'charset=', 6) === FALSE)
+			{
+				$this->dsn .= ';charset='.$this->char_set;
+			}
+
+			$this->subdriver = 'dblib';
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Non-persistent database connection
+	 *
+	 * @param	bool
+	 * @return	object
+	 */
+	public function db_connect($persistent = FALSE)
+	{
+		$this->conn_id = parent::db_connect($persistent);
+
+		if ( ! is_object($this->conn_id))
+		{
+			return $this->conn_id;
+		}
+
+		// Determine how identifiers are escaped
+		$query = $this->query('SELECT CASE WHEN (@@OPTIONS | 256) = @@OPTIONS THEN 1 ELSE 0 END AS qi');
+		$query = $query->row_array();
+		$this->_quoted_identifier = empty($query) ? FALSE : (bool) $query['qi'];
+		$this->_escape_char = ($this->_quoted_identifier) ? '"' : array('[', ']');
+
+		return $this->conn_id;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Show table query
+	 *
+	 * Generates a platform-specific query string so that the table names can be fetched
+	 *
+	 * @param	bool
+	 * @return	string
+	 */
+	protected function _list_tables($prefix_limit = FALSE)
+	{
+		return 'SELECT '.$this->escape_identifiers('name')
+			.' FROM '.$this->escape_identifiers('sysobjects')
+			.' WHERE '.$this->escape_identifiers('type')." = 'U'";
+
+		if ($prefix_limit === TRUE && $this->dbprefix !== '')
+		{
+			$sql .= ' AND '.$this->escape_identifiers('name')." LIKE '".$this->escape_like_str($this->dbprefix)."%' "
+				.sprintf($this->_like_escape_str, $this->_like_escape_chr);
+		}
+
+		return $sql.' ORDER BY '.$this->escape_identifiers('name');
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Show column query
+	 *
+	 * Generates a platform-specific query string so that the column names can be fetched
+	 *
+	 * @param	string	the table name
+	 * @return	string
+	 */
+	protected function _list_columns($table = '')
+	{
+		return 'SELECT '.$this->escape_identifiers('column_name')
+				.' FROM '.$this->escape_identifiers('information_schema.columns')
+				.' WHERE '.$this->escape_identifiers('table_name').' = '.$this->escape($table);
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * From Tables
+	 *
+	 * This function implicitly groups FROM tables so there is no confusion
+	 * about operator precedence in harmony with SQL standards
+	 *
+	 * @param	array
+	 * @return	string
+	 */
+	protected function _from_tables($tables)
+	{
+		return is_array($tables) ? implode(', ', $tables) : $tables;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Update statement
+	 *
+	 * Generates a platform-specific update string from the supplied data
+	 *
+	 * @param	string	the table name
+	 * @param	array	the update data
+	 * @param	array	the where clause
+	 * @param	array	the orderby clause (ignored)
+	 * @param	array	the limit clause (ignored)
+	 * @param	array	the like clause
+	 * @return	string
+         */
+	protected function _update($table, $values, $where, $orderby = array(), $limit = FALSE, $like = array())
+	{
+		foreach ($values as $key => $val)
+		{
+			$valstr[] = $key.' = '.$val;
+		}
+
+		$where = empty($where) ? '' : ' WHERE '.implode(' ', $where);
+
+		if ( ! empty($like))
+		{
+			$where .= ($where === '' ? ' WHERE ' : ' AND ').implode(' ', $like);
+		}
+
+		return 'UPDATE '.$table.' SET '.implode(', ', $valstr).$where;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Delete statement
+	 *
+	 * Generates a platform-specific delete string from the supplied data
+	 *
+	 * @param	string	the table name
+	 * @param	array	the where clause
+	 * @param	array	the like clause
+	 * @param	string	the limit clause
+	 * @return	string
+	 */
+	protected function _delete($table, $where = array(), $like = array(), $limit = FALSE)
+	{
+		$conditions = array();
+
+		empty($where) OR $conditions[] = implode(' ', $where);
+		empty($like) OR $conditions[] = implode(' ', $like);
+
+		$conditions = (count($conditions) > 0) ? ' WHERE '.implode(' AND ', $conditions) : '';
+
+		return ($limit)
+			? 'WITH ci_delete AS (SELECT TOP '.$limit.' * FROM '.$table.$conditions.') DELETE FROM ci_delete'
+			: 'DELETE FROM '.$table.$conditions;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Limit string
+	 *
+	 * Generates a platform-specific LIMIT clause
+	 *
+	 * @param	string	the sql query string
+	 * @param	int	the number of rows to limit the query to
+	 * @param	int	the offset value
+	 * @return	string
+	 */
+	protected function _limit($sql, $limit, $offset)
+	{
+		$limit = $offset + $limit;
+
+		// As of SQL Server 2005 (9.0.*) ROW_NUMBER() is supported,
+		// however an ORDER BY clause is required for it to work
+		if (version_compare($this->version(), '9', '>=') && $offset && ! empty($this->qb_orderby))
+		{
+			$orderby = 'ORDER BY '.implode(', ', $this->qb_orderby);
+
+			// We have to strip the ORDER BY clause
+			$sql = trim(substr($sql, 0, strrpos($sql, 'ORDER BY '.$orderby)));
+
+			return 'SELECT '.(count($this->qb_select) === 0 ? '*' : implode(', ', $this->qb_select))." FROM (\n"
+				.preg_replace('/^(SELECT( DISTINCT)?)/i', '\\1 ROW_NUMBER() OVER('.$orderby.') AS '.$this->escape_identifiers('CI_rownum').', ', $sql)
+				."\n) ".$this->escape_identifiers('CI_subquery')
+				."\nWHERE ".$this->escape_identifiers('CI_rownum').' BETWEEN '.((int) $offset + 1).' AND '.$limit;
+		}
+
+		return preg_replace('/(^\SELECT (DISTINCT)?)/i','\\1 TOP '.$limit.' ', $sql);
+	}
+
+}
+
+/* End of file pdo_dblib_driver.php */
+/* Location: ./system/database/drivers/pdo/subdrivers/pdo_dblib_driver.php */
diff --git a/system/database/drivers/pdo/subdrivers/pdo_firebird_driver.php b/system/database/drivers/pdo/subdrivers/pdo_firebird_driver.php
new file mode 100644
index 000000000..c074a9a78
--- /dev/null
+++ b/system/database/drivers/pdo/subdrivers/pdo_firebird_driver.php
@@ -0,0 +1,262 @@
+<?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 3.0.0
+ * @filesource
+ */
+
+/**
+ * PDO Firebird Database Adapter Class
+ *
+ * Note: _DB is an extender class that the app controller
+ * creates dynamically based on whether the query builder
+ * class is being used or not.
+ *
+ * @package		CodeIgniter
+ * @subpackage	Drivers
+ * @category	Database
+ * @author		EllisLab Dev Team
+ * @link		http://codeigniter.com/user_guide/database/
+ */
+class CI_DB_pdo_firebird_driver extends CI_DB_pdo_driver {
+
+	public $subdriver = 'firebird';
+
+	/**
+	 * The syntax to count rows is slightly different across different
+	 * database engines, so this string appears in each driver and is
+	 * used for the count_all() and count_all_results() functions.
+	 */
+	protected $_random_keyword = ' RANDOM()'; // Currently not supported
+
+	/**
+	 * Constructor
+	 *
+	 * Builds the DSN if not already set.
+	 *
+	 * @param	array
+	 * @return	void
+	 */
+	public function __construct($params)
+	{
+		parent::__construct($params);
+
+		if (empty($this->dsn))
+		{
+			$this->dsn = 'firebird:';
+
+			if ( ! empty($this->database))
+			{
+				$this->dsn .= 'dbname='.$this->database;
+			}
+			elseif ( ! empty($this->hostname))
+			{
+				$this->dsn .= 'dbname='.$this->hostname;
+			}
+
+			empty($this->char_set) OR $this->dsn .= ';charset='.$this->char_set;
+			empty($this->role) OR $this->dsn .= ';role='.$this->role;
+		}
+		elseif ( ! empty($this->char_set) && strpos($this->dsn, 'charset=', 9) === FALSE)
+		{
+			$this->dsn .= ';charset='.$this->char_set;
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Show table query
+	 *
+	 * Generates a platform-specific query string so that the table names can be fetched
+	 *
+	 * @param	bool
+	 * @return	string
+	 */
+	protected function _list_tables($prefix_limit = FALSE)
+	{
+		$sql = 'SELECT "RDB$RELATION_NAME" FROM "RDB$RELATIONS" WHERE "RDB$RELATION_NAME" NOT LIKE \'RDB$%\' AND "RDB$RELATION_NAME" NOT LIKE \'MON$%\'';
+
+		if ($prefix_limit === TRUE && $this->dbprefix !== '')
+		{
+			return $sql.' AND "RDB$RELATION_NAME" LIKE \''.$this->escape_like_str($this->dbprefix)."%' "
+				.sprintf($this->_like_escape_str, $this->_like_escape_chr);
+		}
+
+		return $sql;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Show column query
+	 *
+	 * Generates a platform-specific query string so that the column names can be fetched
+	 *
+	 * @param	string	the table name
+	 * @return	string
+	 */
+	protected function _list_columns($table = '')
+	{
+		return 'SELECT "RDB$FIELD_NAME" FROM "RDB$RELATION_FIELDS" WHERE "RDB$RELATION_NAME" = '.$this->escape($table);
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field data query
+	 *
+	 * Generates a platform-specific query so that the column data can be retrieved
+	 *
+	 * @param	string	the table name
+	 * @return	string
+	 */
+	protected function _field_data($table)
+	{
+		return 'SELECT FIRST 1 * FROM '.$this->protect_identifiers($table);
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * From Tables
+	 *
+	 * This function implicitly groups FROM tables so there is no confusion
+	 * about operator precedence in harmony with SQL standards
+	 *
+	 * @param	array
+	 * @return 	string
+	 */
+	protected function _from_tables($tables)
+	{
+		return is_array($tables) ? implode(', ', $tables) : $tables;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Update statement
+	 *
+	 * Generates a platform-specific update string from the supplied data
+	 *
+	 * @param	string	the table name
+	 * @param	array	the update data
+	 * @param	array	the where clause
+	 * @param	array	the orderby clause
+	 * @param	array	the limit clause (ignored)
+	 * @param	array	the like clause
+	 * @return	string
+	 */
+	protected function _update($table, $values, $where, $orderby = array(), $limit = FALSE, $like = array())
+	{
+		foreach ($values as $key => $val)
+		{
+			$valstr[] = $key.' = '.$val;
+		}
+
+		$where = empty($where) ? '' : ' WHERE '.implode(' ', $where);
+
+		if ( ! empty($like))
+		{
+			$where .= ($where === '' ? ' WHERE ' : ' AND ').implode(' ', $like);
+		}
+
+		return 'UPDATE '.$table.' SET '.implode(', ', $valstr)
+			.$where
+			.(count($orderby) > 0 ? ' ORDER BY '.implode(', ', $orderby) : '');
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Truncate statement
+	 *
+	 * Generates a platform-specific truncate string from the supplied data
+	 *
+	 * If the database does not support the truncate() command,
+	 * then this method maps to 'DELETE FROM table'
+	 *
+	 * @param	string	the table name
+	 * @return	string
+         */
+	protected function _truncate($table)
+	{
+		return 'DELETE FROM '.$table;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Delete statement
+	 *
+	 * Generates a platform-specific delete string from the supplied data
+	 *
+	 * @param	string	the table name
+	 * @param	array	the where clause
+	 * @param	array	the like clause
+	 * @param	string	the limit clause (ignored)
+	 * @return	string
+	 */
+	protected function _delete($table, $where = array(), $like = array(), $limit = FALSE)
+	{
+		$conditions = array();
+
+		empty($where) OR $conditions[] = implode(' ', $where);
+		empty($like) OR $conditions[] = implode(' ', $like);
+
+		return 'DELETE FROM '.$table.(count($conditions) > 0 ? ' WHERE '.implode(' AND ', $conditions) : '');
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Limit string
+	 *
+	 * Generates a platform-specific LIMIT clause
+	 *
+	 * @param	string	the sql query string
+	 * @param	int	the number of rows to limit the query to
+	 * @param	int	the offset value
+	 * @return	string
+	 */
+	protected function _limit($sql, $limit, $offset)
+	{
+		// Limit clause depends on if Interbase or Firebird
+		if (stripos($this->version(), 'firebird') !== FALSE)
+		{
+			$select = 'FIRST '. (int) $limit
+				.($offset > 0 ? ' SKIP '. (int) $offset : '');
+		}
+		else
+		{
+			$select = 'ROWS '
+				.($offset > 0 ? (int) $offset.' TO '.($limit + $offset) : (int) $limit);
+		}
+
+		return preg_replace('`SELECT`i', 'SELECT '.$select, $sql);
+	}
+
+}
+
+/* End of file pdo_firebird_driver.php */
+/* Location: ./system/database/drivers/pdo/subdrivers/pdo_firebird_driver.php */
\ No newline at end of file
diff --git a/system/database/drivers/pdo/subdrivers/pdo_ibm_driver.php b/system/database/drivers/pdo/subdrivers/pdo_ibm_driver.php
new file mode 100644
index 000000000..832c03c96
--- /dev/null
+++ b/system/database/drivers/pdo/subdrivers/pdo_ibm_driver.php
@@ -0,0 +1,262 @@
+<?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 3.0.0
+ * @filesource
+ */
+
+/**
+ * PDO IBM DB2 Database Adapter Class
+ *
+ * Note: _DB is an extender class that the app controller
+ * creates dynamically based on whether the query builder
+ * class is being used or not.
+ *
+ * @package		CodeIgniter
+ * @subpackage	Drivers
+ * @category	Database
+ * @author		EllisLab Dev Team
+ * @link		http://codeigniter.com/user_guide/database/
+ */
+class CI_DB_pdo_ibm_driver extends CI_DB_pdo_driver {
+
+	public $subdriver = 'ibm';
+
+	protected $_random_keyword = ' RAND()';
+
+	/**
+	 * Constructor
+	 *
+	 * Builds the DSN if not already set.
+	 *
+	 * @param	array
+	 * @return	void
+	 */
+	public function __construct($params)
+	{
+		parent::__construct($params);
+
+		if (empty($this->dsn))
+		{
+			$this->dsn = 'ibm:';
+
+			// Pre-defined DSN
+			if (empty($this->hostname) && empty($this->HOSTNAME) && empty($this->port) && empty($this->PORT))
+			{
+				if (isset($this->DSN))
+				{
+					$this->dsn .= 'DSN='.$this->DSN;
+				}
+				elseif ( ! empty($this->database))
+				{
+					$this->dsn .= 'DSN='.$this->database;
+				}
+
+				return;
+			}
+
+			$this->dsn .= 'DRIVER='.(isset($this->DRIVER) ? '{'.$this->DRIVER.'}' : '{IBM DB2 ODBC DRIVER}').';';
+
+			if (isset($this->DATABASE))
+			{
+				$this->dsn .= 'DATABASE='.$this->DATABASE.';';
+			}
+			elseif ( ! empty($this->database))
+			{
+				$this->dsn .= 'DATABASE='.$this->database.';';
+			}
+
+			if (isset($this->HOSTNAME))
+			{
+				$this->dsn .= 'HOSTNAME='.$this->HOSTNAME.';';
+			}
+			else
+			{
+				$this->dsn .= 'HOSTNAME='.(empty($this->hostname) ? '127.0.0.1;' : $this->hostname.';');
+			}
+
+			if (isset($this->PORT))
+			{
+				$this->dsn .= 'PORT='.$this->port.';';
+			}
+			elseif ( ! empty($this->port))
+			{
+				$this->dsn .= ';PORT='.$this->port.';';
+			}
+
+			$this->dsn .= 'PROTOCOL='.(isset($this->PROTOCOL) ? $this->PROTOCOL.';' : 'TCPIP;');
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Show table query
+	 *
+	 * Generates a platform-specific query string so that the table names can be fetched
+	 *
+	 * @param	bool
+	 * @return	string
+	 */
+	protected function _list_tables($prefix_limit = FALSE)
+	{
+		$sql = 'SELECT "tabname" FROM "syscat"."tables" WHERE "type" = \'T\'';
+
+		if ($prefix_limit === TRUE && $this->dbprefix !== '')
+		{
+			$sql .= ' AND "tabname" LIKE \''.$this->escape_like_str($this->dbprefix)."%' "
+				.sprintf($this->_like_escape_str, $this->_like_escape_chr);
+		}
+
+		return $sql;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Show column query
+	 *
+	 * Generates a platform-specific query string so that the column names can be fetched
+	 *
+	 * @param	string	the table name
+	 * @return	string
+	 */
+	protected function _list_columns($table = '')
+	{
+		return 'SELECT "colname" FROM "syscat"."tables"
+			WHERE "syscat"."tabtype" = \'T\' AND "syscat"."tabname" = '.$this->escape($table);
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field data query
+	 *
+	 * Generates a platform-specific query so that the column data can be retrieved
+	 *
+	 * @param	string	the table name
+	 * @return	string
+	 */
+	protected function _field_data($table)
+	{
+		return 'SELECT * FROM '.$this->protect_identifiers($table, TRUE, NULL, FALSE).' FETCH FIRST 1 ROWS ONLY';
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * From Tables
+	 *
+	 * This function implicitly groups FROM tables so there is no confusion
+	 * about operator precedence in harmony with SQL standards
+	 *
+	 * @param	array
+	 * @return	string
+	 */
+	protected function _from_tables($tables)
+	{
+		return is_array($tables) ? implode(', ', $tables) : $tables;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Update statement
+	 *
+	 * Generates a platform-specific update string from the supplied data
+	 *
+	 * @param	string	the table name
+	 * @param	array	the update data
+	 * @param	array	the where clause
+	 * @param	array	the orderby clause (ignored)
+	 * @param	array	the limit clause (ignored)
+	 * @param	array	the like clause
+	 * @return	string
+         */
+	protected function _update($table, $values, $where, $orderby = array(), $limit = FALSE, $like = array())
+	{
+		foreach ($values as $key => $val)
+		{
+			$valstr[] = $key.' = '.$val;
+		}
+
+		$where = empty($where) ? '' : ' WHERE '.implode(' ', $where);
+
+		if ( ! empty($like))
+		{
+			$where .= ($where === '' ? ' WHERE ' : ' AND ').implode(' ', $like);
+		}
+
+		return 'UPDATE '.$table.' SET '.implode(', ', $valstr).$where;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Delete statement
+	 *
+	 * Generates a platform-specific delete string from the supplied data
+	 *
+	 * @param	string	the table name
+	 * @param	array	the where clause
+	 * @param	array	the like clause
+	 * @param	string	the limit clause (ignored)
+	 * @return	string
+	 */
+	protected function _delete($table, $where = array(), $like = array(), $limit = FALSE)
+	{
+		$conditions = array();
+
+		empty($where) OR $conditions[] = implode(' ', $where);
+		empty($like) OR $conditions[] = implode(' ', $like);
+
+		$conditions = (count($conditions) > 0) ? ' WHERE '.implode(' AND ', $conditions) : '';
+
+		return 'DELETE FROM '.$table.$conditions;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Limit string
+	 *
+	 * Generates a platform-specific LIMIT clause
+	 *
+	 * @param	string	the sql query string
+	 * @param	int	the number of rows to limit the query to
+	 * @param	int	the offset value
+	 * @return	string
+	 */
+	protected function _limit($sql, $limit, $offset)
+	{
+		$sql .= ' FETCH FIRST '.($limit + $offset).' ROWS ONLY';
+
+		return ($offset)
+			? 'SELECT * FROM ('.$sql.') WHERE rownum > '.$offset
+			: $sql;
+	}
+
+}
+
+/* End of file pdo_ibm_driver.php */
+/* Location: ./system/database/drivers/pdo/subdrivers/pdo_ibm_driver.php */
\ No newline at end of file
diff --git a/system/database/drivers/pdo/subdrivers/pdo_informix_driver.php b/system/database/drivers/pdo/subdrivers/pdo_informix_driver.php
new file mode 100644
index 000000000..a3efc63dc
--- /dev/null
+++ b/system/database/drivers/pdo/subdrivers/pdo_informix_driver.php
@@ -0,0 +1,271 @@
+<?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 3.0.0
+ * @filesource
+ */
+
+/**
+ * PDO Informix Database Adapter Class
+ *
+ * Note: _DB is an extender class that the app controller
+ * creates dynamically based on whether the query builder
+ * class is being used or not.
+ *
+ * @package		CodeIgniter
+ * @subpackage	Drivers
+ * @category	Database
+ * @author		EllisLab Dev Team
+ * @link		http://codeigniter.com/user_guide/database/
+ */
+class CI_DB_pdo_informix_driver extends CI_DB_pdo_driver {
+
+	public $subdriver = 'informix';
+
+	protected $_random_keyword = ' RAND()';
+
+	/**
+	 * Constructor
+	 *
+	 * Builds the DSN if not already set.
+	 *
+	 * @param	array
+	 * @return	void
+	 */
+	public function __construct($params)
+	{
+		parent::__construct($params);
+
+		if (empty($this->dsn))
+		{
+			$this->dsn = 'informix:';
+
+			// Pre-defined DSN
+			if (empty($this->hostname) && empty($this->host) && empty($this->port) && empty($this->service))
+			{
+				if (isset($this->DSN))
+				{
+					$this->dsn .= 'DSN='.$this->DSN;
+				}
+				elseif ( ! empty($this->database))
+				{
+					$this->dsn .= 'DSN='.$this->database;
+				}
+
+				return;
+			}
+
+			if (isset($this->host))
+			{
+				$this->dsn .= 'host='.$this->host;
+			}
+			else
+			{
+				$this->dsn .= 'host='.(empty($this->hostname) ? '127.0.0.1' : $this->hostname);
+			}
+
+			if (isset($this->service))
+			{
+				$this->dsn .= '; service='.$this->service;
+			}
+			elseif ( ! empty($this->port))
+			{
+				$this->dsn .= '; service='.$this->port;
+			}
+
+			empty($this->database) OR $this->dsn .= '; database='.$this->database;
+			empty($this->server) OR $this->dsn .= '; server='.$this->server;
+
+			$this->dsn .= '; protocol='.(isset($this->protocol) ? $this->protocol : 'onsoctcp')
+				.'; EnableScrollableCursors=1';
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Show table query
+	 *
+	 * Generates a platform-specific query string so that the table names can be fetched
+	 *
+	 * @param	bool
+	 * @return	string
+	 */
+	protected function _list_tables($prefix_limit = FALSE)
+	{
+		$sql = 'SELECT "tabname" FROM "systables" WHERE "tabid" > 99 AND "tabtype" = \'T\'';
+
+		if ($prefix_limit === TRUE && $this->dbprefix !== '')
+		{
+			$sql .= ' AND "tabname" LIKE \''.$this->escape_like_str($this->dbprefix)."%' "
+				.sprintf($this->_like_escape_str, $this->_like_escape_chr);
+		}
+
+		return $sql;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Show column query
+	 *
+	 * Generates a platform-specific query string so that the column names can be fetched
+	 *
+	 * @param	string	the table name
+	 * @return	string
+	 */
+	protected function _list_columns($table = '')
+	{
+		return 'SELECT "colname" FROM "systables", "syscolumns"
+			WHERE "systables"."tabid" = "syscolumns"."tabid" AND "systables"."tabtype" = \'T\' AND "systables"."tabname" = '
+			.$this->escape($table);
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field data query
+	 *
+	 * Generates a platform-specific query so that the column data can be retrieved
+	 *
+	 * @param	string	the table name
+	 * @return	string
+	 */
+	protected function _field_data($table)
+	{
+		return 'SELECT FIRST 1 * FROM '.$this->protect_identifiers($table, TRUE, NULL, FALSE);
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * From Tables
+	 *
+	 * This function implicitly groups FROM tables so there is no confusion
+	 * about operator precedence in harmony with SQL standards
+	 *
+	 * @param	array
+	 * @return	string
+	 */
+	protected function _from_tables($tables)
+	{
+		return is_array($tables) ? implode(', ', $tables) : $tables;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Update statement
+	 *
+	 * Generates a platform-specific update string from the supplied data
+	 *
+	 * @param	string	the table name
+	 * @param	array	the update data
+	 * @param	array	the where clause
+	 * @param	array	the orderby clause (ignored)
+	 * @param	array	the limit clause (ignored)
+	 * @param	array	the like clause
+	 * @return	string
+         */
+	protected function _update($table, $values, $where, $orderby = array(), $limit = FALSE, $like = array())
+	{
+		foreach ($values as $key => $val)
+		{
+			$valstr[] = $key.' = '.$val;
+		}
+
+		$where = empty($where) ? '' : ' WHERE '.implode(' ', $where);
+
+		if ( ! empty($like))
+		{
+			$where .= ($where === '' ? ' WHERE ' : ' AND ').implode(' ', $like);
+		}
+
+		return 'UPDATE '.$table.' SET '.implode(', ', $valstr).$where;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Truncate statement
+	 *
+	 * Generates a platform-specific truncate string from the supplied data
+	 *
+	 * If the database does not support the truncate() command,
+	 * then this method maps to 'DELETE FROM table'
+	 *
+	 * @param	string	the table name
+	 * @return	string
+	 */
+	protected function _truncate($table)
+	{
+		return 'TRUNCATE TABLE ONLY '.$table;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Delete statement
+	 *
+	 * Generates a platform-specific delete string from the supplied data
+	 *
+	 * @param	string	the table name
+	 * @param	array	the where clause
+	 * @param	array	the like clause
+	 * @param	string	the limit clause (ignored)
+	 * @return	string
+	 */
+	protected function _delete($table, $where = array(), $like = array(), $limit = FALSE)
+	{
+		$conditions = array();
+
+		empty($where) OR $conditions[] = implode(' ', $where);
+		empty($like) OR $conditions[] = implode(' ', $like);
+
+		$conditions = (count($conditions) > 0) ? ' WHERE '.implode(' AND ', $conditions) : '';
+
+		return 'DELETE FROM '.$table.$conditions;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Limit string
+	 *
+	 * Generates a platform-specific LIMIT clause
+	 *
+	 * @param	string	the sql query string
+	 * @param	int	the number of rows to limit the query to
+	 * @param	int	the offset value
+	 * @return	string
+	 */
+	protected function _limit($sql, $limit, $offset)
+	{
+		$select = 'SELECT '.($offset ? 'SKIP '.$offset : '').'FIRST '.$limit.' ';
+		return preg_replace('/^(SELECT\s)/i', $select, $sql, 1);
+	}
+
+}
+
+/* End of file pdo_informix_driver.php */
+/* Location: ./system/database/drivers/pdo/subdrivers/pdo_informix_driver.php */
\ No newline at end of file
diff --git a/system/database/drivers/pdo/subdrivers/pdo_mysql_driver.php b/system/database/drivers/pdo/subdrivers/pdo_mysql_driver.php
new file mode 100644
index 000000000..b6807026d
--- /dev/null
+++ b/system/database/drivers/pdo/subdrivers/pdo_mysql_driver.php
@@ -0,0 +1,213 @@
+<?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 3.0.0
+ * @filesource
+ */
+
+/**
+ * PDO MySQL Database Adapter Class
+ *
+ * Note: _DB is an extender class that the app controller
+ * creates dynamically based on whether the query builder
+ * class is being used or not.
+ *
+ * @package		CodeIgniter
+ * @subpackage	Drivers
+ * @category	Database
+ * @author		EllisLab Dev Team
+ * @link		http://codeigniter.com/user_guide/database/
+ */
+class CI_DB_pdo_mysql_driver extends CI_DB_pdo_driver {
+
+	public $subdriver = 'mysql';
+
+	protected $_escape_char = '`';
+
+	protected $_random_keyword = ' RAND()';
+
+	/**
+	 * Constructor
+	 *
+	 * Builds the DSN if not already set.
+	 *
+	 * @param	array
+	 * @return	void
+	 */
+	public function __construct($params)
+	{
+		parent::__construct($params);
+
+		if (empty($this->dsn))
+		{
+			$this->dsn = 'mysql:host='.(empty($this->hostname) ? '127.0.0.1' : $this->hostname);
+
+			empty($this->port) OR $this->dsn .= ';port='.$this->port;
+			empty($this->database) OR $this->dsn .= ';dbname='.$this->database;
+			empty($this->char_set) OR $this->dsn .= ';charset='.$this->char_set;
+		}
+		elseif ( ! empty($this->char_set) && strpos($this->dsn, 'charset=', 6) === FALSE && is_php('5.3.6'))
+		{
+			$this->dsn .= ';charset='.$this->char_set;
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Non-persistent database connection
+	 *
+	 * @param	bool
+	 * @return	object
+	 */
+	public function db_connect($persistent = FALSE)
+	{
+		/* Prior to PHP 5.3.6, even if the charset was supplied in the DSN
+		 * on connect - it was ignored. This is a work-around for the issue.
+		 *
+		 * Reference: http://www.php.net/manual/en/ref.pdo-mysql.connection.php
+		 */
+		if ( ! is_php('5.3.6') && ! empty($this->char_set))
+		{
+			$this->options[PDO::MYSQL_ATTR_INIT_COMMAND] = 'SET NAMES '.$this->char_set
+				.(empty($this->dbcollat) ? '' : ' COLLATE '.$this->dbcollat);
+		}
+
+		return parent::db_connect($persistent);
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Show table query
+	 *
+	 * Generates a platform-specific query string so that the table names can be fetched
+	 *
+	 * @param	bool
+	 * @return	string
+	 */
+	protected function _list_tables($prefix_limit = FALSE)
+	{
+		$sql = 'SHOW TABLES';
+
+		if ($prefix_limit === TRUE && $this->dbprefix !== '')
+		{
+			return $sql." LIKE '".$this->escape_like_str($this->dbprefix)."%'";
+		}
+
+		return $sql;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Show column query
+	 *
+	 * Generates a platform-specific query string so that the column names can be fetched
+	 *
+	 * @param	string	the table name
+	 * @return	string
+	 */
+	protected function _list_columns($table = '')
+	{
+		return 'SHOW COLUMNS FROM '.$this->protect_identifiers($table, TRUE, NULL, FALSE);
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field data query
+	 *
+	 * Generates a platform-specific query so that the column data can be retrieved
+	 *
+	 * @param	string	the table name
+	 * @return	string
+	 */
+	protected function _field_data($table)
+	{
+		return 'SELECT * FROM '.$this->protect_identifiers($table).' LIMIT 1';
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Update_Batch statement
+	 *
+	 * Generates a platform-specific batch update string from the supplied data
+	 *
+	 * @param	string	the table name
+	 * @param	array	the update data
+	 * @param	array	the where clause
+	 * @return	string
+	 */
+	protected function _update_batch($table, $values, $index, $where = NULL)
+	{
+		$ids = array();
+		foreach ($values as $key => $val)
+		{
+			$ids[] = $val[$index];
+
+			foreach (array_keys($val) as $field)
+			{
+				if ($field !== $index)
+				{
+					$final[$field][] =  'WHEN '.$index.' = '.$val[$index].' THEN '.$val[$field];
+				}
+			}
+		}
+
+		$cases = '';
+		foreach ($final as $k => $v)
+		{
+			$cases .= $k." = CASE \n"
+				.implode("\n", $v)."\n"
+				.'ELSE '.$k.' END), ';
+		}
+
+		return 'UPDATE '.$table.' SET '.substr($cases, 0, -2)
+			.' WHERE '.(($where !== '' && count($where) > 0) ? implode(' ', $where).' AND ' : '')
+			.$index.' IN('.implode(',', $ids).')';
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Truncate statement
+	 *
+	 * Generates a platform-specific truncate string from the supplied data
+	 *
+	 * If the database does not support the truncate() command,
+	 * then this method maps to 'DELETE FROM table'
+	 *
+	 * @param	string	the table name
+	 * @return	string
+	 */
+	protected function _truncate($table)
+	{
+		return 'TRUNCATE '.$table;
+	}
+
+}
+
+/* End of file pdo_mysql_driver.php */
+/* Location: ./system/database/drivers/pdo/subdrivers/pdo_mysql_driver.php */
\ No newline at end of file
diff --git a/system/database/drivers/pdo/subdrivers/pdo_oci_driver.php b/system/database/drivers/pdo/subdrivers/pdo_oci_driver.php
new file mode 100644
index 000000000..56ec1bce1
--- /dev/null
+++ b/system/database/drivers/pdo/subdrivers/pdo_oci_driver.php
@@ -0,0 +1,230 @@
+<?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 3.0.0
+ * @filesource
+ */
+
+/**
+ * PDO Oracle Database Adapter Class
+ *
+ * Note: _DB is an extender class that the app controller
+ * creates dynamically based on whether the query builder
+ * class is being used or not.
+ *
+ * @package		CodeIgniter
+ * @subpackage	Drivers
+ * @category	Database
+ * @author		EllisLab Dev Team
+ * @link		http://codeigniter.com/user_guide/database/
+ */
+class CI_DB_pdo_oci_driver extends CI_DB_pdo_driver {
+
+	public $subdriver = 'oci';
+
+	/**
+	 * The syntax to count rows is slightly different across different
+	 * database engines, so this string appears in each driver and is
+	 * used for the count_all() and count_all_results() functions.
+	 */
+	protected $_count_string = 'SELECT COUNT(1) AS ';
+	protected $_random_keyword = ' ASC'; // Currently not supported
+
+	protected $_reserved_identifiers = array('*', 'rownum');
+
+	/**
+	 * Constructor
+	 *
+	 * Builds the DSN if not already set.
+	 *
+	 * @param	array
+	 * @return	void
+	 */
+	public function __construct($params)
+	{
+		parent::__construct($params);
+
+		if (empty($this->dsn))
+		{
+			$this->dsn = 'oci:dbname=';
+
+			// Oracle has a slightly different PDO DSN format (Easy Connect),
+			// which also supports pre-defined DSNs.
+			if (empty($this->hostname) && empty($this->port))
+			{
+				$this->dsn .= $this->database;
+			}
+			else
+			{
+				$this->dsn .= '//'.(empty($this->hostname) ? '127.0.0.1' : $this->hostname)
+					.(empty($this->port) ? '' : ':'.$this->port).'/';
+
+				empty($this->database) OR $this->dsn .= $this->database;
+			}
+
+			empty($this->char_set) OR $this->dsn .= ';charset='.$this->char_set;
+		}
+		elseif ( ! empty($this->char_set) && strpos($this->dsn, 'charset=', 4) === FALSE)
+		{
+			$this->dsn .= ';charset='.$this->char_set;
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Show table query
+	 *
+	 * Generates a platform-specific query string so that the table names can be fetched
+	 *
+	 * @param	bool
+	 * @return	string
+	 */
+	protected function _list_tables($prefix_limit = FALSE)
+	{
+		$sql = 'SELECT "TABLE_NAME" FROM "ALL_TABLES"';
+
+		if ($prefix_limit === TRUE && $this->dbprefix !== '')
+		{
+			return $sql.' WHERE "TABLE_NAME" LIKE \''.$this->escape_like_str($this->dbprefix)."%' "
+				.sprintf($this->_like_escape_str, $this->_like_escape_chr);
+		}
+
+		return $sql;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Show column query
+	 *
+	 * Generates a platform-specific query string so that the column names can be fetched
+	 *
+	 * @param	string	the table name
+	 * @return	string
+	 */
+	protected function _list_columns($table = '')
+	{
+		return 'SELECT "COLUMN_NAME" FROM "all_tab_columns" WHERE "TABLE_NAME" = '.$this->escape($table);
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field data query
+	 *
+	 * Generates a platform-specific query so that the column data can be retrieved
+	 *
+	 * @param	string	the table name
+	 * @return	string
+	 */
+	protected function _field_data($table)
+	{
+		return 'SELECT * FROM '.$this->protect_identifiers($table).' WHERE rownum = 1';
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * From Tables
+	 *
+	 * This function implicitly groups FROM tables so there is no confusion
+	 * about operator precedence in harmony with SQL standards
+	 *
+	 * @param	array
+	 * @return	string
+	 */
+	protected function _from_tables($tables)
+	{
+		return is_array($tables) ? implode(', ', $tables) : $tables;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Insert_batch statement
+	 *
+	 * @param	string	the table name
+	 * @param	array	the insert keys
+	 * @param	array	the insert values
+	 * @return 	string
+	 */
+	protected function _insert_batch($table, $keys, $values)
+	{
+		$keys = implode(', ', $keys);
+		$sql = "INSERT ALL\n";
+
+		for ($i = 0, $c = count($values); $i < $c; $i++)
+		{
+			$sql .= '	INTO '.$table.' ('.$keys.') VALUES '.$values[$i]."\n";
+		}
+
+		return $sql.'SELECT * FROM dual';
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Delete statement
+	 *
+	 * Generates a platform-specific delete string from the supplied data
+	 *
+	 * @param	string	the table name
+	 * @param	array	the where clause
+	 * @param	array	the like clause
+	 * @param	string	the limit clause
+	 * @return	string
+	 */
+	protected function _delete($table, $where = array(), $like = array(), $limit = FALSE)
+	{
+		$conditions = array();
+
+		empty($where) OR $conditions[] = implode(' ', $where);
+		empty($like) OR $conditions[] = implode(' ', $like);
+		empty($limit) OR $conditions[] = 'rownum <= '.$limit;
+
+		return 'DELETE FROM '.$table.(count($conditions) > 0 ? ' WHERE '.implode(' AND ', $conditions) : '');
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Limit string
+	 *
+	 * Generates a platform-specific LIMIT clause
+	 *
+	 * @param	string	the sql query string
+	 * @param	int	the number of rows to limit the query to
+	 * @param	int	the offset value
+	 * @return	string
+	 */
+	protected function _limit($sql, $limit, $offset)
+	{
+		return 'SELECT * FROM (SELECT inner_query.*, rownum rnum FROM ('.$sql.') inner_query WHERE rownum < '.($offset + $limit + 1).')'
+			.($offset ? ' WHERE rnum >= '.($offset + 1): '');
+	}
+
+}
+
+/* End of file pdo_oci_driver.php */
+/* Location: ./system/database/drivers/pdo/subdrivers/pdo_oci_driver.php */
\ No newline at end of file
diff --git a/system/database/drivers/pdo/subdrivers/pdo_odbc_driver.php b/system/database/drivers/pdo/subdrivers/pdo_odbc_driver.php
new file mode 100644
index 000000000..dd7a1af52
--- /dev/null
+++ b/system/database/drivers/pdo/subdrivers/pdo_odbc_driver.php
@@ -0,0 +1,267 @@
+<?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 3.0.0
+ * @filesource
+ */
+
+/**
+ * PDO ODBC Database Adapter Class
+ *
+ * Note: _DB is an extender class that the app controller
+ * creates dynamically based on whether the query builder
+ * class is being used or not.
+ *
+ * @package		CodeIgniter
+ * @subpackage	Drivers
+ * @category	Database
+ * @author		EllisLab Dev Team
+ * @link		http://codeigniter.com/user_guide/database/
+ */
+class CI_DB_pdo_odbc_driver extends CI_DB_pdo_driver {
+
+	public $subdriver = 'odbc';
+
+	// The character used for escaping - not used in ODBC
+	protected $_escape_char = '';
+
+	// clause and character used for LIKE escape sequences
+	protected $_like_escape_str = " {escape '%s'} ";
+
+	protected $_random_keyword = ' RAND()';
+
+	/**
+	 * Constructor
+	 *
+	 * Builds the DSN if not already set.
+	 *
+	 * @param	array
+	 * @return	void
+	 */
+	public function __construct($params)
+	{
+		parent::__construct($params);
+
+		if (empty($this->dsn))
+		{
+			$this->dsn = 'odbc:';
+
+			// Pre-defined DSN
+			if (empty($this->hostname) && empty($this->HOSTNAME) && empty($this->port) && empty($this->PORT))
+			{
+				if (isset($this->DSN))
+				{
+					$this->dsn .= 'DSN='.$this->DSN;
+				}
+				elseif ( ! empty($this->database))
+				{
+					$this->dsn .= 'DSN='.$this->database;
+				}
+
+				return;
+			}
+
+			// If the DSN is not pre-configured - try to build an IBM DB2 connection string
+			$this->dsn .= 'DRIVER='.(isset($this->DRIVER) ? '{'.$this->DRIVER.'}' : '{IBM DB2 ODBC DRIVER}').';';
+
+			if (isset($this->DATABASE))
+			{
+				$this->dsn .= 'DATABASE='.$this->DATABASE.';';
+			}
+			elseif ( ! empty($this->database))
+			{
+				$this->dsn .= 'DATABASE='.$this->database.';';
+			}
+
+			if (isset($this->HOSTNAME))
+			{
+				$this->dsn .= 'HOSTNAME='.$this->HOSTNAME.';';
+			}
+			else
+			{
+				$this->dsn .= 'HOSTNAME='.(empty($this->hostname) ? '127.0.0.1;' : $this->hostname.';');
+			}
+
+			if (isset($this->PORT))
+			{
+				$this->dsn .= 'PORT='.$this->port.';';
+			}
+			elseif ( ! empty($this->port))
+			{
+				$this->dsn .= ';PORT='.$this->port.';';
+			}
+
+			$this->dsn .= 'PROTOCOL='.(isset($this->PROTOCOL) ? $this->PROTOCOL.';' : 'TCPIP;');
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Show table query
+	 *
+	 * Generates a platform-specific query string so that the table names can be fetched
+	 *
+	 * @param	bool
+	 * @return	string
+	 */
+	protected function _list_tables($prefix_limit = FALSE)
+	{
+		$sql = "SELECT table_name FROM information_schema.tables WHERE table_schema = 'public'";
+
+		if ($prefix_limit !== FALSE && $this->dbprefix !== '')
+		{
+			return $sql." AND table_name LIKE '".$this->escape_like_str($this->dbprefix)."%' "
+				.sprintf($this->_like_escape_str, $this->_like_escape_chr);
+		}
+
+                return $sql;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Show column query
+	 *
+	 * Generates a platform-specific query string so that the column names can be fetched
+	 *
+	 * @param	string	the table name
+	 * @return	string
+	 */
+	protected function _list_columns($table = '')
+	{
+		return 'SELECT column_name FROM information_schema.columns WHERE table_name = '.$this->escape($table);
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * From Tables
+	 *
+	 * This function implicitly groups FROM tables so there is no confusion
+	 * about operator precedence in harmony with SQL standards
+	 *
+	 * @param	array
+	 * @return	string
+	 */
+	protected function _from_tables($tables)
+	{
+		return is_array($tables) ? implode(', ', $tables) : $tables;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Update statement
+	 *
+	 * Generates a platform-specific update string from the supplied data
+	 *
+	 * @param	string	the table name
+	 * @param	array	the update data
+	 * @param	array	the where clause
+	 * @param	array	the orderby clause (ignored)
+	 * @param	array	the limit clause (ignored)
+	 * @param	array	the like clause
+	 * @return	string
+         */
+	protected function _update($table, $values, $where, $orderby = array(), $limit = FALSE, $like = array())
+	{
+		foreach ($values as $key => $val)
+		{
+			$valstr[] = $key.' = '.$val;
+		}
+
+		$where = empty($where) ? '' : ' WHERE '.implode(' ', $where);
+
+		if ( ! empty($like))
+		{
+			$where .= ($where === '' ? ' WHERE ' : ' AND ').implode(' ', $like);
+		}
+
+		return 'UPDATE '.$table.' SET '.implode(', ', $valstr).$where;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Truncate statement
+	 *
+	 * Generates a platform-specific truncate string from the supplied data
+	 *
+	 * If the database does not support the truncate() command,
+	 * then this method maps to 'DELETE FROM table'
+	 *
+	 * @param	string	the table name
+	 * @return	string
+	 */
+	protected function _truncate($table)
+	{
+		return 'DELETE FROM '.$table;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Delete statement
+	 *
+	 * Generates a platform-specific delete string from the supplied data
+	 *
+	 * @param	string	the table name
+	 * @param	array	the where clause
+	 * @param	array	the like clause
+	 * @param	string	the limit clause
+	 * @return	string
+	 */
+	protected function _delete($table, $where = array(), $like = array(), $limit = FALSE)
+	{
+		$conditions = array();
+
+		empty($where) OR $conditions[] = implode(' ', $where);
+		empty($like) OR $conditions[] = implode(' ', $like);
+
+		$conditions = (count($conditions) > 0) ? ' WHERE '.implode(' AND ', $conditions) : '';
+
+		return 'DELETE FROM '.$table.$conditions;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Limit string
+	 *
+	 * Generates a platform-specific LIMIT clause
+	 *
+	 * @param	string	the sql query string
+	 * @param	int	the number of rows to limit the query to
+	 * @param	int	the offset value
+	 * @return	string
+	 */
+	protected function _limit($sql, $limit, $offset)
+	{
+		return preg_replace('/(^\SELECT (DISTINCT)?)/i','\\1 TOP '.$limit.' ', $sql);
+	}
+
+}
+
+/* End of file pdo_odbc_driver.php */
+/* Location: ./system/database/drivers/pdo/subdrivers/pdo_odbc_driver.php */
\ No newline at end of file
diff --git a/system/database/drivers/pdo/subdrivers/pdo_pgsql_driver.php b/system/database/drivers/pdo/subdrivers/pdo_pgsql_driver.php
new file mode 100644
index 000000000..9a476f143
--- /dev/null
+++ b/system/database/drivers/pdo/subdrivers/pdo_pgsql_driver.php
@@ -0,0 +1,341 @@
+<?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 3.0.0
+ * @filesource
+ */
+
+/**
+ * PDO PostgreSQL Database Adapter Class
+ *
+ * Note: _DB is an extender class that the app controller
+ * creates dynamically based on whether the query builder
+ * class is being used or not.
+ *
+ * @package		CodeIgniter
+ * @subpackage	Drivers
+ * @category	Database
+ * @author		EllisLab Dev Team
+ * @link		http://codeigniter.com/user_guide/database/
+ */
+class CI_DB_pdo_pgsql_driver extends CI_DB_pdo_driver {
+
+	public $subdriver = 'pgsql';
+
+	protected $_random_keyword = ' RANDOM()';
+
+	/**
+	 * Constructor
+	 *
+	 * Builds the DSN if not already set.
+	 *
+	 * @param	array
+	 * @return	void
+	 */
+	public function __construct($params)
+	{
+		parent::__construct($params);
+
+		if (empty($this->dsn))
+		{
+			$this->dsn = 'pgsql:host='.(empty($this->hostname) ? '127.0.0.1' : $this->hostname);
+
+			empty($this->port) OR $this->dsn .= ';port='.$this->port;
+			empty($this->database) OR $this->dsn .= ';dbname='.$this->database;
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Insert ID
+	 *
+	 * @param	string
+	 * @return	int
+	 */
+	public function insert_id($name = NULL)
+	{
+		if ($name === NULL && version_compare($this->version(), '8.1', '>='))
+		{
+			$query = $this->query('SELECT LASTVAL() AS ins_id');
+			$query = $query->row();
+			return $query->ins_id;
+		}
+
+		return $this->conn_id->lastInsertId($name);
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Show table query
+	 *
+	 * Generates a platform-specific query string so that the table names can be fetched
+	 *
+	 * @param	bool
+	 * @return	string
+	 */
+	protected function _list_tables($prefix_limit = FALSE)
+	{
+		$sql = 'SELECT "table_name" FROM "information_schema"."tables" WHERE "table_schema" = \'public\'';
+
+		if ($prefix_limit === TRUE && $this->dbprefix !== '')
+		{
+			return $sql.' AND "table_name" LIKE \''
+				.$this->escape_like_str($this->dbprefix)."%' "
+				.sprintf($this->_like_escape_str, $this->_like_escape_chr);
+		}
+
+		return $sql;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Show column query
+	 *
+	 * Generates a platform-specific query string so that the column names can be fetched
+	 *
+	 * @param	string	the table name
+	 * @return	string
+	 */
+	protected function _list_columns($table = '')
+	{
+		return 'SELECT "column_name" FROM "information_schema"."columns" WHERE "table_name" = '.$this->escape($table);
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field data query
+	 *
+	 * Generates a platform-specific query so that the column data can be retrieved
+	 *
+	 * @param	string	the table name
+	 * @return	string
+	 */
+	protected function _field_data($table)
+	{
+		return 'SELECT * FROM '.$this->protect_identifiers($table).' LIMIT 1';
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * From Tables
+	 *
+	 * This function implicitly groups FROM tables so there is no confusion
+	 * about operator precedence in harmony with SQL standards
+	 *
+	 * @param	array
+	 * @return	string
+	 */
+	protected function _from_tables($tables)
+	{
+		return is_array($tables) ? implode(', ', $tables) : $tables;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Update statement
+	 *
+	 * Generates a platform-specific update string from the supplied data
+	 *
+	 * @param	string	the table name
+	 * @param	array	the update data
+	 * @param	array	the where clause
+	 * @param	array	the orderby clause (ignored)
+	 * @param	array	the limit clause (ignored)
+	 * @param	array	the like clause
+	 * @return	string
+         */
+	protected function _update($table, $values, $where, $orderby = array(), $limit = FALSE, $like = array())
+	{
+		foreach ($values as $key => $val)
+		{
+			$valstr[] = $key.' = '.$val;
+		}
+
+		$where = empty($where) ? '' : ' WHERE '.implode(' ', $where);
+
+		if ( ! empty($like))
+		{
+			$where .= ($where === '' ? ' WHERE ' : ' AND ').implode(' ', $like);
+		}
+
+		return 'UPDATE '.$table.' SET '.implode(', ', $valstr).$where;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Update_Batch statement
+	 *
+	 * Generates a platform-specific batch update string from the supplied data
+	 *
+	 * @param	string	the table name
+	 * @param	array	the update data
+	 * @param	array	the where clause
+	 * @return	string
+	 */
+	protected function _update_batch($table, $values, $index, $where = NULL)
+	{
+		$ids = array();
+		foreach ($values as $key => $val)
+		{
+			$ids[] = $val[$index];
+
+			foreach (array_keys($val) as $field)
+			{
+				if ($field !== $index)
+				{
+					$final[$field][] =  'WHEN '.$val[$index].' THEN '.$val[$field];
+				}
+			}
+		}
+
+		$cases = '';
+		foreach ($final as $k => $v)
+		{
+			$cases .= $k.' = (CASE '.$k."\n"
+				.implode("\n", $v)."\n"
+				.'ELSE '.$k.' END), ';
+		}
+
+		return 'UPDATE '.$table.' SET '.substr($cases, 0, -2)
+			.' WHERE '.(($where !== '' && count($where) > 0) ? implode(' ', $where).' AND ' : '')
+			.$index.' IN('.implode(',', $ids).')';
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Delete statement
+	 *
+	 * Generates a platform-specific delete string from the supplied data
+	 *
+	 * @param	string	the table name
+	 * @param	array	the where clause
+	 * @param	array	the like clause
+	 * @param	string	the limit clause (ignored)
+	 * @return	string
+	 */
+	protected function _delete($table, $where = array(), $like = array(), $limit = FALSE)
+	{
+		$conditions = array();
+
+		empty($where) OR $conditions[] = implode(' ', $where);
+		empty($like) OR $conditions[] = implode(' ', $like);
+
+		return 'DELETE FROM '.$table.(count($conditions) > 0 ? ' WHERE '.implode(' AND ', $conditions) : '');
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Limit string
+	 *
+	 * Generates a platform-specific LIMIT clause
+	 *
+	 * @param	string	the sql query string
+	 * @param	int	the number of rows to limit the query to
+	 * @param	int	the offset value
+	 * @return	string
+	 */
+	protected function _limit($sql, $limit, $offset)
+	{
+		return $sql.' LIMIT '.$limit.($offset ? ' OFFSET '.$offset : '');
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Where
+	 *
+	 * Called by where() or or_where()
+	 *
+	 * @param	mixed
+	 * @param	mixed
+	 * @param	string
+	 * @return	object
+	 */
+	protected function _where($key, $value = NULL, $type = 'AND ', $escape = NULL)
+	{
+		if ( ! is_array($key))
+		{
+			$key = array($key => $value);
+		}
+
+		// If the escape value was not set will will base it on the global setting
+		is_bool($escape) OR $escape = $this->_protect_identifiers;
+
+		foreach ($key as $k => $v)
+		{
+			$prefix = (count($this->qb_where) === 0 && count($this->qb_cache_where) === 0)
+				? $this->_group_get_type('')
+				: $this->_group_get_type($type);
+
+			$k = (($op = $this->_get_operator($k)) !== FALSE)
+				? $this->protect_identifiers(substr($k, 0, strpos($k, $op)), FALSE, $escape).strstr($k, $op)
+				: $this->protect_identifiers($k, FALSE, $escape);
+
+			if (is_null($v) && ! $this->_has_operator($k))
+			{
+				// value appears not to have been set, assign the test to IS NULL
+				$k .= ' IS NULL';
+			}
+
+			if ( ! is_null($v))
+			{
+				if ($escape === TRUE)
+				{
+					$v = ' '.$this->escape($v);
+				}
+				elseif (is_bool($v))
+				{
+					$v = ($v ? ' TRUE' : ' FALSE');
+				}
+
+				if ( ! $this->_has_operator($k))
+				{
+					$k .= ' = ';
+				}
+			}
+
+			$this->qb_where[] = $prefix.$k.$v;
+			if ($this->qb_caching === TRUE)
+			{
+				$this->qb_cache_where[] = $prefix.$k.$v;
+				$this->qb_cache_exists[] = 'where';
+			}
+
+		}
+
+		return $this;
+	}
+
+}
+
+/* End of file pdo_pgsql_driver.php */
+/* Location: ./system/database/drivers/pdo/subdrivers/pdo_pgsql_driver.php */
\ No newline at end of file
diff --git a/system/database/drivers/pdo/subdrivers/pdo_sqlite_driver.php b/system/database/drivers/pdo/subdrivers/pdo_sqlite_driver.php
new file mode 100644
index 000000000..bf0363f63
--- /dev/null
+++ b/system/database/drivers/pdo/subdrivers/pdo_sqlite_driver.php
@@ -0,0 +1,167 @@
+<?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 3.0.0
+ * @filesource
+ */
+
+/**
+ * PDO SQLite Database Adapter Class
+ *
+ * Note: _DB is an extender class that the app controller
+ * creates dynamically based on whether the query builder
+ * class is being used or not.
+ *
+ * @package		CodeIgniter
+ * @subpackage	Drivers
+ * @category	Database
+ * @author		EllisLab Dev Team
+ * @link		http://codeigniter.com/user_guide/database/
+ */
+class CI_DB_pdo_sqlite_driver extends CI_DB_pdo_driver {
+
+	public $subdriver = 'sqlite';
+
+	/**
+	 * The syntax to count rows is slightly different across different
+	 * database engines, so this string appears in each driver and is
+	 * used for the count_all() and count_all_results() functions.
+	 */
+	protected $_random_keyword = ' RANDOM()'; // Currently not supported
+
+	/**
+	 * Constructor
+	 *
+	 * Builds the DSN if not already set.
+	 *
+	 * @param	array
+	 * @return	void
+	 */
+	public function __construct($params)
+	{
+		parent::__construct($params);
+
+		if (empty($this->dsn))
+		{
+			$this->dsn = 'sqlite:';
+
+			if (empty($this->database) && empty($this->hostname))
+			{
+				$this->database = ':memory:';
+			}
+
+			$this->database = empty($this->database) ? $this->hostname : $this->database;
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Show table query
+	 *
+	 * Generates a platform-specific query string so that the table names can be fetched
+	 *
+	 * @param	bool
+	 * @return	string
+	 */
+	protected function _list_tables($prefix_limit = FALSE)
+	{
+		$sql = 'SELECT "NAME" FROM "SQLITE_MASTER" WHERE "TYPE" = \'table\'';
+
+		if ($prefix_limit === TRUE && $this->dbprefix !== '')
+		{
+			return $sql.' AND "NAME" LIKE \''.$this->escape_like_str($this->dbprefix)."%' "
+				.sprintf($this->_like_escape_str, $this->_like_escape_chr);
+		}
+
+		return $sql;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Show column query
+	 *
+	 * Generates a platform-specific query string so that the column names can be fetched
+	 *
+	 * @param	string	the table name
+	 * @return	string
+	 */
+	protected function _list_columns($table = '')
+	{
+		// Not supported
+		return FALSE;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Field data query
+	 *
+	 * Generates a platform-specific query so that the column data can be retrieved
+	 *
+	 * @param	string	the table name
+	 * @return	string
+	 */
+	protected function _field_data($table)
+	{
+		return 'SELECT * FROM '.$this->protect_identifiers($table).' LIMIT 0,1';
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Replace statement
+	 *
+	 * @param	string	the table name
+	 * @param	array	the insert keys
+	 * @param	array	the insert values
+	 * @return 	string
+	 */
+	protected function _replace($table, $keys, $values)
+	{
+		return 'INSERT OR '.parent::_replace($table, $keys, $values);
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Truncate statement
+	 *
+	 * Generates a platform-specific truncate string from the supplied data
+	 *
+	 * If the database does not support the truncate() command,
+	 * then this method maps to 'DELETE FROM table'
+	 *
+	 * @param	string	the table name
+	 * @return	string
+         */
+	protected function _truncate($table)
+	{
+		return 'DELETE FROM '.$table;
+	}
+
+}
+
+/* End of file pdo_sqlite_driver.php */
+/* Location: ./system/database/drivers/pdo/subdrivers/pdo_sqlite_driver.php */
\ No newline at end of file
diff --git a/system/database/drivers/pdo/subdrivers/pdo_sqlsrv_driver.php b/system/database/drivers/pdo/subdrivers/pdo_sqlsrv_driver.php
new file mode 100644
index 000000000..f125b8f50
--- /dev/null
+++ b/system/database/drivers/pdo/subdrivers/pdo_sqlsrv_driver.php
@@ -0,0 +1,299 @@
+<?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 3.0.0
+ * @filesource
+ */
+
+/**
+ * PDO SQLSRV Database Adapter Class
+ *
+ * Note: _DB is an extender class that the app controller
+ * creates dynamically based on whether the query builder
+ * class is being used or not.
+ *
+ * @package		CodeIgniter
+ * @subpackage	Drivers
+ * @category	Database
+ * @author		EllisLab Dev Team
+ * @link		http://codeigniter.com/user_guide/database/
+ */
+class CI_DB_pdo_sqlsrv_driver extends CI_DB_pdo_driver {
+
+	public $subdriver = 'sqlsrv';
+
+	protected $_random_keyword = ' NEWID()';
+
+	protected $_quoted_identifier;
+
+	/**
+	 * Constructor
+	 *
+	 * Builds the DSN if not already set.
+	 *
+	 * @param	array
+	 * @return	void
+	 */
+	public function __construct($params)
+	{
+		parent::__construct($params);
+
+		if (empty($this->dsn))
+		{
+			$this->dsn = 'sqlsrv:Server='.(empty($this->hostname) ? '127.0.0.1' : $this->hostname);
+
+			empty($this->port) OR $this->dsn .= ','.$this->port;
+			empty($this->database) OR $this->dsn .= ';Database='.$this->database;
+
+			// Some custom options
+
+			if (isset($this->QuotedId))
+			{
+				$this->dsn .= ';QuotedId='.$this->QuotedId;
+				$this->_quoted_identifier = (bool) $this->QuotedId;
+			}
+
+			if (isset($this->ConnectionPooling))
+			{
+				$this->dsn .= ';ConnectionPooling='.$this->ConnectionPooling;
+			}
+
+			if (isset($this->Encrypt))
+			{
+				$this->dsn .= ';Encrypt='.$this->Encrypt;
+			}
+
+			if (isset($this->TraceOn))
+			{
+				$this->dsn .= ';TraceOn='.$this->TraceOn;
+			}
+
+			if (isset($this->TrustServerCertificate))
+			{
+				$this->dsn .= ';TrustServerCertificate='.$this->TrustServerCertificate;
+			}
+
+			empty($this->APP) OR $this->dsn .= ';APP='.$this->APP;
+			empty($this->Failover_Partner) OR $this->dsn .= ';Failover_Partner='.$this->Failover_Partner;
+			empty($this->LoginTimeout) OR $this->dsn .= ';LoginTimeout='.$this->LoginTimeout;
+			empty($this->MultipleActiveResultSets) OR $this->dsn .= ';MultipleActiveResultSets='.$this->MultipleActiveResultSets;
+			empty($this->TraceFile) OR $this->dsn .= ';TraceFile='.$this->TraceFile;
+			empty($this->WSID) OR $this->dsn .= ';WSID='.$this->WSID;
+		}
+		elseif (preg_match('/QuotedId=(0|1)/', $this->dsn, $match))
+		{
+			$this->_quoted_identifier = (bool) $match[1];
+		}
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Non-persistent database connection
+	 *
+	 * @param	bool
+	 * @return	object
+	 */
+	public function db_connect($persistent = FALSE)
+	{
+		if ( ! empty($this->char_set) && preg_match('/utf[^8]*8/i', $this->char_set))
+		{
+			$this->options[PDO::SQLSRV_ENCODING_UTF8] = 1;
+		}
+
+		$this->conn_id = parent::db_connect($persistent);
+
+		if ( ! is_object($this->conn_id) OR is_bool($this->_quoted_identifier))
+		{
+			return $this->conn_id;
+		}
+
+		// Determine how identifiers are escaped
+		$query = $this->query('SELECT CASE WHEN (@@OPTIONS | 256) = @@OPTIONS THEN 1 ELSE 0 END AS qi');
+		$query = $query->row_array();
+		$this->_quoted_identifier = empty($query) ? FALSE : (bool) $query['qi'];
+		$this->_escape_char = ($this->_quoted_identifier) ? '"' : array('[', ']');
+
+		return $this->conn_id;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Show table query
+	 *
+	 * Generates a platform-specific query string so that the table names can be fetched
+	 *
+	 * @param	bool
+	 * @return	string
+	 */
+	protected function _list_tables($prefix_limit = FALSE)
+	{
+		return 'SELECT '.$this->escape_identifiers('name')
+			.' FROM '.$this->escape_identifiers('sysobjects')
+			.' WHERE '.$this->escape_identifiers('type')." = 'U'";
+
+		if ($prefix_limit === TRUE && $this->dbprefix !== '')
+		{
+			$sql .= ' AND '.$this->escape_identifiers('name')." LIKE '".$this->escape_like_str($this->dbprefix)."%' "
+				.sprintf($this->_like_escape_str, $this->_like_escape_chr);
+		}
+
+		return $sql.' ORDER BY '.$this->escape_identifiers('name');
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Show column query
+	 *
+	 * Generates a platform-specific query string so that the column names can be fetched
+	 *
+	 * @param	string	the table name
+	 * @return	string
+	 */
+	protected function _list_columns($table = '')
+	{
+		return 'SELECT '.$this->escape_identifiers('column_name')
+			.' FROM '.$this->escape_identifiers('information_schema.columns')
+			.' WHERE '.$this->escape_identifiers('table_name').' = '.$this->escape($table);
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * From Tables
+	 *
+	 * This function implicitly groups FROM tables so there is no confusion
+	 * about operator precedence in harmony with SQL standards
+	 *
+	 * @param	array
+	 * @return	string
+	 */
+	protected function _from_tables($tables)
+	{
+		return is_array($tables) ? implode(', ', $tables) : $tables;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Update statement
+	 *
+	 * Generates a platform-specific update string from the supplied data
+	 *
+	 * @param	string	the table name
+	 * @param	array	the update data
+	 * @param	array	the where clause
+	 * @param	array	the orderby clause (ignored)
+	 * @param	array	the limit clause (ignored)
+	 * @param	array	the like clause
+	 * @return	string
+         */
+	protected function _update($table, $values, $where, $orderby = array(), $limit = FALSE, $like = array())
+	{
+		foreach ($values as $key => $val)
+		{
+			$valstr[] = $key.' = '.$val;
+		}
+
+		$where = empty($where) ? '' : ' WHERE '.implode(' ', $where);
+
+		if ( ! empty($like))
+		{
+			$where .= ($where === '' ? ' WHERE ' : ' AND ').implode(' ', $like);
+		}
+
+		return 'UPDATE '.$table.' SET '.implode(', ', $valstr).$where;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Delete statement
+	 *
+	 * Generates a platform-specific delete string from the supplied data
+	 *
+	 * @param	string	the table name
+	 * @param	array	the where clause
+	 * @param	array	the like clause
+	 * @param	string	the limit clause
+	 * @return	string
+	 */
+	protected function _delete($table, $where = array(), $like = array(), $limit = FALSE)
+	{
+		$conditions = array();
+
+		empty($where) OR $conditions[] = implode(' ', $where);
+		empty($like) OR $conditions[] = implode(' ', $like);
+
+		$conditions = (count($conditions) > 0) ? ' WHERE '.implode(' AND ', $conditions) : '';
+
+		return ($limit)
+			? 'WITH ci_delete AS (SELECT TOP '.$limit.' * FROM '.$table.$conditions.') DELETE FROM ci_delete'
+			: 'DELETE FROM '.$table.$conditions;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Limit string
+	 *
+	 * Generates a platform-specific LIMIT clause
+	 *
+	 * @param	string	the sql query string
+	 * @param	int	the number of rows to limit the query to
+	 * @param	int	the offset value
+	 * @return	string
+	 */
+	protected function _limit($sql, $limit, $offset)
+	{
+		// As of SQL Server 2012 (11.0.*) OFFSET is supported
+		if (version_compare($this->version(), '11', '>='))
+		{
+			return $sql.' OFFSET '.(int) $offset.' ROWS FETCH NEXT '.(int) $limit.' ROWS ONLY';
+		}
+
+		$limit = $offset + $limit;
+
+		// An ORDER BY clause is required for ROW_NUMBER() to work
+		if ($offset && ! empty($this->qb_orderby))
+		{
+			$orderby = 'ORDER BY '.implode(', ', $this->qb_orderby);
+
+			// We have to strip the ORDER BY clause
+			$sql = trim(substr($sql, 0, strrpos($sql, 'ORDER BY '.$orderby)));
+
+			return 'SELECT '.(count($this->qb_select) === 0 ? '*' : implode(', ', $this->qb_select))." FROM (\n"
+				.preg_replace('/^(SELECT( DISTINCT)?)/i', '\\1 ROW_NUMBER() OVER('.$orderby.') AS '.$this->escape_identifiers('CI_rownum').', ', $sql)
+				."\n) ".$this->escape_identifiers('CI_subquery')
+				."\nWHERE ".$this->escape_identifiers('CI_rownum').' BETWEEN '.((int) $offset + 1).' AND '.$limit;
+		}
+
+		return preg_replace('/(^\SELECT (DISTINCT)?)/i','\\1 TOP '.$limit.' ', $sql);
+	}
+
+}
+
+/* End of file pdo_sqlsrv_driver.php */
+/* Location: ./system/database/drivers/pdo/subdrivers/pdo_sqlsrv_driver.php */