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

Conflicts:
	user_guide_src/source/changelog.rst

37 files changed, 1020 insertions, 1208 deletions

diff --git a/system/database/DB_cache.php b/system/database/DB_cache.php
index ba9110382..d07c755c6 100644
--- a/system/database/DB_cache.php
+++ b/system/database/DB_cache.php
@@ -37,12 +37,20 @@ class CI_DB_Cache {
 	public $CI;
 	public $db;	// allows passing of db object so that multiple database connections and returned db objects can be supported
 
+	/**
+	 * Constructor
+	 *
+	 * @param	object	&$db
+	 * @return	void
+	 */
 	public function __construct(&$db)
 	{
 		// Assign the main CI object to $this->CI and load the file helper since we use it a lot
 		$this->CI =& get_instance();
 		$this->db =& $db;
 		$this->CI->load->helper('file');
+
+		$this->check_path();
 	}
 
 	// --------------------------------------------------------------------
@@ -66,7 +74,9 @@ class CI_DB_Cache {
 		}
 
 		// Add a trailing slash to the path if needed
-		$path = preg_replace('/(.+?)\/*$/', '\\1/',  $path);
+		$path = realpath($path)
+			? rtrim(realpath($path), DIRECTORY_SEPARATOR).DIRECTORY_SEPARATOR
+			: rtrim($path, '/').'/';
 
 		if ( ! is_dir($path) OR ! is_really_writable($path))
 		{
@@ -86,15 +96,11 @@ class CI_DB_Cache {
 	 * The URI being requested will become the name of the cache sub-folder.
 	 * An MD5 hash of the SQL statement will become the cache file name
 	 *
+	 * @param	string	$sql
 	 * @return	string
 	 */
 	public function read($sql)
 	{
-		if ( ! $this->check_path())
-		{
-			return $this->db->cache_off();
-		}
-
 		$segment_one = ($this->CI->uri->segment(1) == FALSE) ? 'default' : $this->CI->uri->segment(1);
 		$segment_two = ($this->CI->uri->segment(2) == FALSE) ? 'index' : $this->CI->uri->segment(2);
 		$filepath = $this->db->cachedir.$segment_one.'+'.$segment_two.'/'.md5($sql);
@@ -112,15 +118,12 @@ class CI_DB_Cache {
 	/**
 	 * Write a query to a cache file
 	 *
+	 * @param	string	$sql
+	 * @param	object	$object
 	 * @return	bool
 	 */
 	public function write($sql, $object)
 	{
-		if ( ! $this->check_path())
-		{
-			return $this->db->cache_off();
-		}
-
 		$segment_one = ($this->CI->uri->segment(1) == FALSE) ? 'default' : $this->CI->uri->segment(1);
 		$segment_two = ($this->CI->uri->segment(2) == FALSE) ? 'index' : $this->CI->uri->segment(2);
 		$dir_path = $this->db->cachedir.$segment_one.'+'.$segment_two.'/';
@@ -150,7 +153,9 @@ class CI_DB_Cache {
 	/**
 	 * Delete cache files within a particular directory
 	 *
-	 * @return	bool
+	 * @param	string	$segment_one = ''
+	 * @param	string	$segment_two = ''
+	 * @return	void
 	 */
 	public function delete($segment_one = '', $segment_two = '')
 	{
@@ -173,7 +178,7 @@ class CI_DB_Cache {
 	/**
 	 * Delete all existing cache files
 	 *
-	 * @return	bool
+	 * @return	void
 	 */
 	public function delete_all()
 	{
diff --git a/system/database/DB_driver.php b/system/database/DB_driver.php
index d63a1d955..7f1434fc1 100644
--- a/system/database/DB_driver.php
+++ b/system/database/DB_driver.php
@@ -51,6 +51,7 @@ abstract class CI_DB_driver {
 	public $char_set		= 'utf8';
 	public $dbcollat		= 'utf8_general_ci';
 	public $autoinit		= TRUE; // Whether to automatically initialize the DB
+	public $encrypt			= FALSE;
 	public $swap_pre		= '';
 	public $port			= '';
 	public $pconnect		= FALSE;
@@ -78,6 +79,10 @@ abstract class CI_DB_driver {
 	protected $_protect_identifiers		= TRUE;
 	protected $_reserved_identifiers	= array('*'); // Identifiers that should NOT be escaped
 
+	// 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
@@ -305,8 +310,9 @@ abstract class CI_DB_driver {
 	 * FALSE upon failure, and if the $db_debug variable is set to TRUE
 	 * will raise an error.
 	 *
-	 * @param	string	An SQL query string
-	 * @param	array	An array of binding data
+	 * @param	string	$sql
+	 * @param	array	$binds = FALSE		An array of binding data
+	 * @param	bool	$return_object = NULL
 	 * @return	mixed
 	 */
 	public function query($sql, $binds = FALSE, $return_object = NULL)
@@ -509,6 +515,7 @@ abstract class CI_DB_driver {
 	 * If strict mode is disabled, each group is treated autonomously, meaning
 	 * a failure of one group will not affect any others
 	 *
+	 * @param	bool	$mode = TRUE
 	 * @return	void
 	 */
 	public function trans_strict($mode = TRUE)
@@ -521,6 +528,7 @@ abstract class CI_DB_driver {
 	/**
 	 * Start Transaction
 	 *
+	 * @param	bool	$test_mode = FALSE
 	 * @return	void
 	 */
 	public function trans_start($test_mode = FALSE)
@@ -669,7 +677,7 @@ abstract class CI_DB_driver {
 	 */
 	public function is_write_type($sql)
 	{
-		return (bool) preg_match('/^\s*"?(SET|INSERT|UPDATE|DELETE|REPLACE|CREATE|DROP|TRUNCATE|LOAD DATA|COPY|ALTER|RENAME|GRANT|REVOKE|LOCK|UNLOCK|REINDEX)\s+/i', $sql);
+		return (bool) preg_match('/^\s*"?(SET|INSERT|UPDATE|DELETE|REPLACE|CREATE|DROP|TRUNCATE|LOAD|COPY|ALTER|RENAME|GRANT|REVOKE|LOCK|UNLOCK|REINDEX)\s+/i', $sql);
 	}
 
 	// --------------------------------------------------------------------
@@ -805,6 +813,7 @@ abstract class CI_DB_driver {
 	/**
 	 * Returns an array of table names
 	 *
+	 * @param	string	$constrain_by_prefix = FALSE
 	 * @return	array
 	 */
 	public function list_tables($constrain_by_prefix = FALSE)
@@ -859,6 +868,7 @@ abstract class CI_DB_driver {
 	/**
 	 * Determine if a particular table exists
 	 *
+	 * @param	string	$table_name
 	 * @return	bool
 	 */
 	public function table_exists($table_name)
@@ -1119,30 +1129,19 @@ abstract class CI_DB_driver {
 	 *
 	 * @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
-	 * @param	array	the like clause
 	 * @return	string
 	 */
-	protected function _update($table, $values, $where, $orderby = array(), $limit = FALSE, $like = array())
+	protected function _update($table, $values)
 	{
 		foreach ($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(', ', $orderby) : '')
-			.($limit ? ' LIMIT '.$limit : '');
+			.$this->_compile_wh('qb_where')
+			.$this->_compile_order_by()
+			.($this->qb_limit ? ' LIMIT '.$this->qb_limit : '');
 	}
 
 	// --------------------------------------------------------------------
@@ -1155,7 +1154,7 @@ abstract class CI_DB_driver {
 	 */
 	protected function _has_operator($str)
 	{
-		return (bool) preg_match('/(\s|<|>|!|=|IS NULL|IS NOT NULL|BETWEEN)/i', trim($str));
+		return (bool) preg_match('/(<|>|!|=|\sIS NULL|\sIS NOT NULL|\sBETWEEN|\sLIKE|\sIN\s*\(|\s)/i', trim($str));
 	}
 
 	// --------------------------------------------------------------------
@@ -1168,8 +1167,30 @@ abstract class CI_DB_driver {
 	 */
 	protected function _get_operator($str)
 	{
-		return preg_match('/(=|!|<|>| IS NULL| IS NOT NULL| BETWEEN)/i', $str, $match)
-			? $match[1] : FALSE;
+		static $_operators;
+
+		if (empty($_operators))
+		{
+			$_les = ($this->_like_escape_str !== '')
+				? '\s+'.preg_quote(trim(sprintf($this->_like_escape_str, $this->_like_escape_chr)))
+				: '';
+			$_operators = array(
+				'\s*(?:<|>|!)?=\s*',		// =, <=, >=, !=
+				'\s*<>?\s*',			// <, <>
+				'\s*>\s*',			// >
+				'\s+IS NULL',			// IS NULL
+				'\s+IS NOT NULL',		// IS NOT NULL
+				'\s+BETWEEN\s+\S+\s+AND\s+\S+',	// BETWEEN value AND value
+				'\s+IN\s*\([^\)]+\)',		// IN(list)
+				'\s+NOT IN\s*\([^\)]+\)',	// NOT IN (list)
+				'\s+LIKE\s+\S+'.$_les,		// LIKE 'expr'[ ESCAPE '%s']
+				'\s+NOT LIKE\s+\S+'.$_les	// NOT LIKE 'expr'[ ESCAPE '%s']
+			);
+
+		}
+
+		return preg_match('/'.implode('|', $_operators).'/i', $str, $match)
+			? $match[0] : FALSE;
 	}
 
 	// --------------------------------------------------------------------
@@ -1177,8 +1198,8 @@ abstract class CI_DB_driver {
 	/**
 	 * Enables a native PHP function to be run, using a platform agnostic wrapper.
 	 *
-	 * @param	string	the function name
-	 * @param	mixed	any parameters needed by the function
+	 * @param	string	$function	the function name
+	 * @param	mixed	$param,...	optional parameters needed by the function
 	 * @return	mixed
 	 */
 	public function call_function($function)
@@ -1242,6 +1263,8 @@ abstract class CI_DB_driver {
 	/**
 	 * Delete the cache files associated with a particular URI
 	 *
+	 * @param	string	$segment_one = ''
+	 * @param	string	$segment_two = ''
 	 * @return	bool
 	 */
 	public function cache_delete($segment_one = '', $segment_two = '')
@@ -1343,7 +1366,7 @@ abstract class CI_DB_driver {
 		}
 		else
 		{
-			$message = ( ! is_array($error)) ? array(str_replace('%s', $swap, $LANG->line($error))) : $error;
+			$message = is_array($error) ? $error : array(str_replace('%s', $swap, $LANG->line($error)));
 		}
 
 		// Find the most likely culprit of the error by going through
@@ -1352,7 +1375,13 @@ abstract class CI_DB_driver {
 		$trace = debug_backtrace();
 		foreach ($trace as $call)
 		{
-			if (isset($call['file']) && strpos($call['file'], BASEPATH.'database') === FALSE)
+			// We'll need this on Windows, as APPPATH and BASEPATH will always use forward slashes
+			if (DIRECTORY_SEPARATOR !== '/')
+			{
+				$call['file'] = str_replace('\\', '/', $call['file']);
+			}
+
+			if (isset($call['file'], $call['class']) && strpos($call['file'], BASEPATH.'database') === FALSE && strpos($call['class'], 'Loader') !== FALSE)
 			{
 				// Found it - use a relative path for safety
 				$message[] = 'Filename: '.str_replace(array(APPPATH, BASEPATH), '', $call['file']);
diff --git a/system/database/DB_forge.php b/system/database/DB_forge.php
index 91f9d560c..119d78d38 100644
--- a/system/database/DB_forge.php
+++ b/system/database/DB_forge.php
@@ -37,7 +37,7 @@ abstract class CI_DB_forge {
 	public $fields		= array();
 	public $keys		= array();
 	public $primary_keys	= array();
-	public $db_char_set	=	'';
+	public $db_char_set	= '';
 
 	// Platform specific SQL strings
 	protected $_create_database	= 'CREATE DATABASE %s';
@@ -45,6 +45,11 @@ abstract class CI_DB_forge {
 	protected $_drop_table		= 'DROP TABLE IF EXISTS %s';
 	protected $_rename_table	= 'ALTER TABLE %s RENAME TO %s';
 
+	/**
+	 * Constructor
+	 *
+	 * @return	void
+	 */
 	public function __construct()
 	{
 		// Assign the main database object to $this->db
@@ -206,7 +211,8 @@ abstract class CI_DB_forge {
 	/**
 	 * Create Table
 	 *
-	 * @param	string	the table name
+	 * @param	string	$table = ''
+	 * @param	bool	$if_not_exists = FALSE
 	 * @return	bool
 	 */
 	public function create_table($table = '', $if_not_exists = FALSE)
@@ -378,9 +384,8 @@ abstract class CI_DB_forge {
 	/**
 	 * Column Modify
 	 *
-	 * @param	string	the table name
-	 * @param	string	the column name
-	 * @param	string	the column definition
+	 * @param	string	$table = ''
+	 * @param	string	$field = array()	column definition
 	 * @return	bool
 	 */
 	public function modify_column($table = '', $field = array())
diff --git a/system/database/DB_query_builder.php b/system/database/DB_query_builder.php
index 479b7f24a..5ea9643fe 100644
--- a/system/database/DB_query_builder.php
+++ b/system/database/DB_query_builder.php
@@ -47,7 +47,6 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	protected $qb_from			= array();
 	protected $qb_join			= array();
 	protected $qb_where			= array();
-	protected $qb_like			= array();
 	protected $qb_groupby			= array();
 	protected $qb_having			= array();
 	protected $qb_keys			= array();
@@ -55,7 +54,6 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	protected $qb_offset			= FALSE;
 	protected $qb_orderby			= array();
 	protected $qb_set			= array();
-	protected $qb_wherein			= array();
 	protected $qb_aliased_tables		= array();
 	protected $qb_store_array		= array();
 	protected $qb_where_group_started	= FALSE;
@@ -184,15 +182,17 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	// --------------------------------------------------------------------
 
 	/**
-	 * Processing Function for the four functions above:
+	 * Processing Function for the following functions:
 	 *
 	 *	select_max()
 	 *	select_min()
 	 *	select_avg()
 	 *	select_sum()
 	 *
-	 * @param	string	the field
-	 * @param	string	an alias
+	 *
+	 * @param	string	$select = ''	field name
+	 * @param	string	$alias = ''
+	 * @param	string	$type = 'MAX'
 	 * @return	object
 	 */
 	protected function _max_min_avg_sum($select = '', $alias = '', $type = 'MAX')
@@ -417,7 +417,7 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	 */
 	public function where($key, $value = NULL, $escape = NULL)
 	{
-		return $this->_where($key, $value, 'AND ', $escape);
+		return $this->_wh('qb_where', $key, $value, 'AND ', $escape);
 	}
 
 	// --------------------------------------------------------------------
@@ -435,24 +435,27 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	 */
 	public function or_where($key, $value = NULL, $escape = NULL)
 	{
-		return $this->_where($key, $value, 'OR ', $escape);
+		return $this->_wh('qb_where', $key, $value, 'OR ', $escape);
 	}
 
 	// --------------------------------------------------------------------
 
 	/**
-	 * Where
+	 * WHERE, HAVING
 	 *
-	 * Called by where() or or_where()
+	 * Called by where(), or_where(), having(), or_having()
 	 *
+	 * @param	string	'qb_where' or 'qb_having'
 	 * @param	mixed
 	 * @param	mixed
 	 * @param	string
-	 * @param	mixed
+	 * @param	bool
 	 * @return	object
 	 */
-	protected function _where($key, $value = NULL, $type = 'AND ', $escape = NULL)
+	protected function _wh($qb_key, $key, $value = NULL, $type = 'AND ', $escape = NULL)
 	{
+		$qb_cache_key = ($qb_key === 'qb_having') ? 'qb_cache_having' : 'qb_cache_where';
+
 		if ( ! is_array($key))
 		{
 			$key = array($key => $value);
@@ -463,17 +466,10 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 
 		foreach ($key as $k => $v)
 		{
-			$prefix = (count($this->qb_where) === 0 && count($this->qb_cache_where) === 0)
+			$prefix = (count($this->$qb_key) === 0 && count($this->$qb_cache_key) === 0)
 				? $this->_group_get_type('')
 				: $this->_group_get_type($type);
 
-			if ($escape === TRUE)
-			{
-				$k = (($op = $this->_get_operator($k)) !== FALSE)
-					? $this->escape_identifiers(trim(substr($k, 0, strpos($k, $op)))).' '.strstr($k, $op)
-					: $this->escape_identifiers(trim($k));
-			}
-
 			if (is_null($v) && ! $this->_has_operator($k))
 			{
 				// value appears not to have been set, assign the test to IS NULL
@@ -484,7 +480,7 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 			{
 				if ($escape === TRUE)
 				{
-					$v = ' '.$this->escape($v);
+					$v = ' '.(is_int($v) ? $v : $this->escape($v));
 				}
 
 				if ( ! $this->_has_operator($k))
@@ -493,11 +489,11 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 				}
 			}
 
-			$this->qb_where[] = $prefix.$k.$v;
+			$this->{$qb_key}[] = array('condition' => $prefix.$k.$v, 'escape' => $escape);
 			if ($this->qb_caching === TRUE)
 			{
-				$this->qb_cache_where[] = $prefix.$k.$v;
-				$this->qb_cache_exists[] = 'where';
+				$this->{$qb_cache_key}[] = array('condition' => $prefix.$k.$v, 'escape' => $escape);
+				$this->qb_cache_exists[] = substr($qb_key, 3);
 			}
 
 		}
@@ -510,11 +506,12 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	/**
 	 * Where_in
 	 *
-	 * Generates a WHERE field IN ('item', 'item') SQL query joined with
+	 * Generates a WHERE field IN('item', 'item') SQL query joined with
 	 * AND if appropriate
 	 *
-	 * @param	string	The field to search
-	 * @param	array	The values searched on
+	 * @param	string	$key = NULL	The field to search
+	 * @param	array	$values = NULL	The values searched on
+	 * @param	bool	$escape = NULL
 	 * @return	object
 	 */
 	public function where_in($key = NULL, $values = NULL, $escape = NULL)
@@ -525,13 +522,14 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	// --------------------------------------------------------------------
 
 	/**
-	 * Where_in_or
+	 * Or_where_in
 	 *
-	 * Generates a WHERE field IN ('item', 'item') SQL query joined with
+	 * Generates a WHERE field IN('item', 'item') SQL query joined with
 	 * OR if appropriate
 	 *
-	 * @param	string	The field to search
-	 * @param	array	The values searched on
+	 * @param	string	$key = NULL	The field to search
+	 * @param	array	$values = NULL	The values searched on
+	 * @param	bool	$escape = NULL
 	 * @return	object
 	 */
 	public function or_where_in($key = NULL, $values = NULL, $escape = NULL)
@@ -544,11 +542,12 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	/**
 	 * Where_not_in
 	 *
-	 * Generates a WHERE field NOT IN ('item', 'item') SQL query joined
+	 * Generates a WHERE field NOT IN('item', 'item') SQL query joined
 	 * with AND if appropriate
 	 *
-	 * @param	string	The field to search
-	 * @param	array	The values searched on
+	 * @param	string	$key = NULL	The field to search
+	 * @param	array	$values = NULL	The values searched on
+	 * @param	bool	$escape = NULL
 	 * @return	object
 	 */
 	public function where_not_in($key = NULL, $values = NULL, $escape = NULL)
@@ -559,13 +558,14 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	// --------------------------------------------------------------------
 
 	/**
-	 * Where_not_in_or
+	 * Or_where_not_in
 	 *
-	 * Generates a WHERE field NOT IN ('item', 'item') SQL query joined
+	 * Generates a WHERE field NOT IN('item', 'item') SQL query joined
 	 * with OR if appropriate
 	 *
-	 * @param	string	The field to search
-	 * @param	array	The values searched on
+	 * @param	string	$key = NULL	The field to search
+	 * @param	array	$values = NULL	The values searched on
+	 * @param	bool	$escape = NULL
 	 * @return	object
 	 */
 	public function or_where_not_in($key = NULL, $values = NULL, $escape = NULL)
@@ -578,12 +578,13 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	/**
 	 * Where_in
 	 *
-	 * Called by where_in, where_in_or, where_not_in, where_not_in_or
+	 * Called by where_in(), or_where_in(), where_not_in(), or_where_not_in()
 	 *
-	 * @param	string	The field to search
-	 * @param	array	The values searched on
-	 * @param	bool	If the statement would be IN or NOT IN
-	 * @param	string
+	 * @param	string	$key = NULL	The field to search
+	 * @param	array	$values = NULL	The values searched on
+	 * @param	bool	$not = FALSE	If the statement would be IN or NOT IN
+	 * @param	string	$type = 'AND '
+	 * @param	bool	$escape = NULL
 	 * @return	object
 	 */
 	protected function _where_in($key = NULL, $values = NULL, $not = FALSE, $type = 'AND ', $escape = NULL)
@@ -602,27 +603,25 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 
 		$not = ($not) ? ' NOT' : '';
 
+		$where_in = array();
 		foreach ($values as $value)
 		{
-			$this->qb_wherein[] = $this->escape($value);
-		}
-
-		if ($escape === TRUE)
-		{
-			$key = $this->escape_identifiers(trim($key));
+			$where_in[] = $this->escape($value);
 		}
 
 		$prefix = (count($this->qb_where) === 0) ? $this->_group_get_type('') : $this->_group_get_type($type);
-		$this->qb_where[] = $where_in = $prefix.$key.$not.' IN ('.implode(', ', $this->qb_wherein).') ';
+		$where_in = array(
+			'condition' => $prefix.$key.$not.' IN('.implode(', ', $where_in).')',
+			'escape' => $escape
+		);
 
+		$this->qb_where[] = $where_in;
 		if ($this->qb_caching === TRUE)
 		{
 			$this->qb_cache_where[] = $where_in;
 			$this->qb_cache_exists[] = 'where';
 		}
 
-		// reset the array for multiple calls
-		$this->qb_wherein = array();
 		return $this;
 	}
 
@@ -635,12 +634,14 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	 * multiple calls with AND
 	 *
 	 * @param	mixed
-	 * @param	mixed
+	 * @param	string
+	 * @param	string
+	 * @param	bool
 	 * @return	object
 	 */
-	public function like($field, $match = '', $side = 'both')
+	public function like($field, $match = '', $side = 'both', $escape = NULL)
 	{
-		return $this->_like($field, $match, 'AND ', $side);
+		return $this->_like($field, $match, 'AND ', $side, '', $escape);
 	}
 
 	// --------------------------------------------------------------------
@@ -652,12 +653,14 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	 * multiple calls with AND
 	 *
 	 * @param	mixed
-	 * @param	mixed
+	 * @param	string
+	 * @param	string
+	 * @param	bool
 	 * @return	object
 	 */
-	public function not_like($field, $match = '', $side = 'both')
+	public function not_like($field, $match = '', $side = 'both', $escape = NULL)
 	{
-		return $this->_like($field, $match, 'AND ', $side, 'NOT');
+		return $this->_like($field, $match, 'AND ', $side, 'NOT', $escape);
 	}
 
 	// --------------------------------------------------------------------
@@ -669,12 +672,14 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	 * multiple calls with OR
 	 *
 	 * @param	mixed
-	 * @param	mixed
+	 * @param	string
+	 * @param	string
+	 * @param	bool
 	 * @return	object
 	 */
-	public function or_like($field, $match = '', $side = 'both')
+	public function or_like($field, $match = '', $side = 'both', $escape = NULL)
 	{
-		return $this->_like($field, $match, 'OR ', $side);
+		return $this->_like($field, $match, 'OR ', $side, '', $escape);
 	}
 
 	// --------------------------------------------------------------------
@@ -686,12 +691,14 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	 * multiple calls with OR
 	 *
 	 * @param	mixed
-	 * @param	mixed
+	 * @param	string
+	 * @param	string
+	 * @param	bool
 	 * @return	object
 	 */
-	public function or_not_like($field, $match = '', $side = 'both')
+	public function or_not_like($field, $match = '', $side = 'both', $escape = NULL)
 	{
-		return $this->_like($field, $match, 'OR ', $side, 'NOT');
+		return $this->_like($field, $match, 'OR ', $side, 'NOT', $escape);
 	}
 
 	// --------------------------------------------------------------------
@@ -699,56 +706,60 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	/**
 	 * Like
 	 *
-	 * Called by like() or orlike()
+	 * Called by like(), or_like(), not_like, or_not_like()
 	 *
 	 * @param	mixed
-	 * @param	mixed
 	 * @param	string
+	 * @param	string
+	 * @param	string
+	 * @param	string
+	 * @param	bool
 	 * @return	object
 	 */
-	protected function _like($field, $match = '', $type = 'AND ', $side = 'both', $not = '')
+	protected function _like($field, $match = '', $type = 'AND ', $side = 'both', $not = '', $escape = NULL)
 	{
 		if ( ! is_array($field))
 		{
 			$field = array($field => $match);
 		}
 
+		is_bool($escape) OR $escape = $this->_protect_identifiers;
+		$prefix = (count($this->qb_where) === 0 && count($this->qb_cache_where) === 0)
+			? $this->_group_get_type('') : $this->_group_get_type($type);
+
 		foreach ($field as $k => $v)
 		{
-			$k = $this->protect_identifiers($k);
-			$prefix = (count($this->qb_like) === 0) ? $this->_group_get_type('') : $this->_group_get_type($type);
 			$v = $this->escape_like_str($v);
 
 			if ($side === 'none')
 			{
-				$like_statement = "{$prefix} $k $not LIKE '{$v}'";
+				$like_statement = "{$prefix} {$k} {$not} LIKE '{$v}'";
 			}
 			elseif ($side === 'before')
 			{
-				$like_statement = "{$prefix} $k $not LIKE '%{$v}'";
+				$like_statement = "{$prefix} {$k} {$not} LIKE '%{$v}'";
 			}
 			elseif ($side === 'after')
 			{
-				$like_statement = "{$prefix} $k $not LIKE '{$v}%'";
+				$like_statement = "{$prefix} {$k} {$not} LIKE '{$v}%'";
 			}
 			else
 			{
-				$like_statement = "{$prefix} $k $not LIKE '%{$v}%'";
+				$like_statement = "{$prefix} {$k} {$not} LIKE '%{$v}%'";
 			}
 
 			// some platforms require an escape sequence definition for LIKE wildcards
 			if ($this->_like_escape_str !== '')
 			{
-				$like_statement = $like_statement.sprintf($this->_like_escape_str, $this->_like_escape_chr);
+				$like_statement .= sprintf($this->_like_escape_str, $this->_like_escape_chr);
 			}
 
-			$this->qb_like[] = $like_statement;
+			$this->qb_where[] = array('condition' => $like_statement, 'escape' => $escape);
 			if ($this->qb_caching === TRUE)
 			{
-				$this->qb_cache_like[] = $like_statement;
-				$this->qb_cache_exists[] = 'like';
+				$this->qb_cache_where[] = $like_statement;
+				$this->qb_cache_exists[] = 'where';
 			}
-
 		}
 
 		return $this;
@@ -769,11 +780,15 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 
 		$this->qb_where_group_started = TRUE;
 		$prefix = (count($this->qb_where) === 0 && count($this->qb_cache_where) === 0) ? '' : $type;
-		$this->qb_where[] = $value = $prefix.$not.str_repeat(' ', ++$this->qb_where_group_count).' (';
+		$where = array(
+			'condition' => $prefix.$not.str_repeat(' ', ++$this->qb_where_group_count).' (',
+			'escape' => FALSE
+		);
 
+		$this->qb_where[] = $where;
 		if ($this->qb_caching)
 		{
-			$this->qb_cache_where[] = $value;
+			$this->qb_cache_where[] = $where;
 		}
 
 		return $this;
@@ -825,11 +840,15 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	public function group_end()
 	{
 		$this->qb_where_group_started = FALSE;
-		$this->qb_where[] = $value = str_repeat(' ', $this->qb_where_group_count--) . ')';
+		$where = array(
+			'condition' => str_repeat(' ', $this->qb_where_group_count--).')',
+			'escape' => FALSE
+		);
 
+		$this->qb_where[] = $where;
 		if ($this->qb_caching)
 		{
-			$this->qb_cache_where[] = $value;
+			$this->qb_cache_where[] = $where;
 		}
 
 		return $this;
@@ -862,13 +881,18 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	 * GROUP BY
 	 *
 	 * @param	string
+	 * @param	bool
 	 * @return	object
 	 */
-	public function group_by($by)
+	public function group_by($by, $escape = NULL)
 	{
+		is_bool($escape) OR $escape = $this->_protect_identifiers;
+
 		if (is_string($by))
 		{
-			$by = explode(',', $by);
+			$by = ($escape === TRUE)
+				? explode(',', $by)
+				: array($by);
 		}
 
 		foreach ($by as $val)
@@ -877,8 +901,9 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 
 			if ($val !== '')
 			{
-				$this->qb_groupby[] = $val = $this->protect_identifiers($val);
+				$val = array('field' => $val, 'escape' => $escape);
 
+				$this->qb_groupby[] = $val;
 				if ($this->qb_caching === TRUE)
 				{
 					$this->qb_cache_groupby[] = $val;
@@ -902,9 +927,9 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	 * @param	bool
 	 * @return	object
 	 */
-	public function having($key, $value = '', $escape = NULL)
+	public function having($key, $value = NULL, $escape = NULL)
 	{
-		return $this->_having($key, $value, 'AND ', $escape);
+		return $this->_wh('qb_having', $key, $value, 'AND ', $escape);
 	}
 
 	// --------------------------------------------------------------------
@@ -919,60 +944,9 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	 * @param	bool
 	 * @return	object
 	 */
-	public function or_having($key, $value = '', $escape = NULL)
+	public function or_having($key, $value = NULL, $escape = NULL)
 	{
-		return $this->_having($key, $value, 'OR ', $escape);
-	}
-
-	// --------------------------------------------------------------------
-
-	/**
-	 * Sets the HAVING values
-	 *
-	 * Called by having() or or_having()
-	 *
-	 * @param	string
-	 * @param	string
-	 * @param	string
-	 * @param	bool
-	 * @return	object
-	 */
-	protected function _having($key, $value = '', $type = 'AND ', $escape = NULL)
-	{
-		if ( ! is_array($key))
-		{
-			$key = array($key => $value);
-		}
-
-		is_bool($escape) OR $escape = $this->_protect_identifiers;
-
-		foreach ($key as $k => $v)
-		{
-			$prefix = (count($this->qb_having) === 0) ? '' : $type;
-
-			$k = $this->_has_operator($k)
-				? $this->protect_identifiers(substr($k, 0, strpos(rtrim($k), ' ')), FALSE, $escape).strchr(rtrim($k), ' ')
-				: $this->protect_identifiers($k, FALSE, $escape);
-
-			if ( ! $this->_has_operator($k))
-			{
-				$k .= ' = ';
-			}
-
-			if ($v !== '')
-			{
-				$v = ' '.$this->escape($v);
-			}
-
-			$this->qb_having[] = $prefix.$k.$v;
-			if ($this->qb_caching === TRUE)
-			{
-				$this->qb_cache_having[] = $prefix.$k.$v;
-				$this->qb_cache_exists[] = 'having';
-			}
-		}
-
-		return $this;
+		return $this->_wh('qb_having', $key, $value, 'OR ', $escape);
 	}
 
 	// --------------------------------------------------------------------
@@ -981,54 +955,50 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	 * Sets the ORDER BY value
 	 *
 	 * @param	string
-	 * @param	string	direction: asc or desc
+	 * @param	string	direction: ASC or DESC
 	 * @param	bool	enable field name escaping
 	 * @return	object
 	 */
 	public function order_by($orderby, $direction = '', $escape = NULL)
 	{
-		if (strtolower($direction) === 'random')
+		$direction = trim($direction);
+
+		if (strtolower($direction) === 'random' OR $orderby === $this->_random_keyword)
+		{
+			// Random ordered results don't need a field name
+			$orderby = $this->_random_keyword;
+			$direction = '';
+		}
+		elseif (empty($orderby))
 		{
-			$orderby = ''; // Random results want or don't need a field name
-			$direction = $this->_random_keyword;
+			return $this;
 		}
-		elseif (trim($direction) !== '')
+		elseif ($direction !== '')
 		{
-			$direction = in_array(strtoupper(trim($direction)), array('ASC', 'DESC'), TRUE) ? ' '.$direction : ' ASC';
+			$direction = in_array(strtoupper(trim($direction)), array('ASC', 'DESC'), TRUE) ? ' '.$direction : '';
 		}
 
 		is_bool($escape) OR $escape = $this->_protect_identifiers;
 
-		if ($escape === TRUE && strpos($orderby, ',') !== FALSE)
+		if ($escape === FALSE)
 		{
-			$temp = array();
-			foreach (explode(',', $orderby) as $part)
-			{
-				$part = trim($part);
-				if ( ! in_array($part, $this->qb_aliased_tables))
-				{
-					$part = preg_match('/^(.+)\s+(ASC|DESC)$/i', $part, $matches)
-						? $this->protect_identifiers(rtrim($matches[1])).' '.$matches[2]
-						: $this->protect_identifiers($part);
-				}
-
-				$temp[] = $part;
-			}
-
-			$orderby = implode(', ', $temp);
+			$qb_orderby[] = array('field' => $orderby, 'direction' => $direction, 'escape' => FALSE);
 		}
-		elseif ($direction !== $this->_random_keyword && $escape === TRUE)
+		else
 		{
-			$orderby = preg_match('/^(.+)\s+(ASC|DESC)$/i', $orderby, $matches)
-				? $this->protect_identifiers(rtrim($matches[1])).' '.$matches[2]
-				: $this->protect_identifiers($orderby);
+			$qb_orderby = array();
+			foreach (explode(',', $orderby) as $field)
+			{
+				$qb_orderby[] = ($direction === '' && preg_match('/\s+(ASC|DESC)$/i', rtrim($field), $match, PREG_OFFSET_CAPTURE))
+					? array('field' => ltrim(substr($field, 0, $match[0][1])), 'direction' => ' '.$match[1][0], 'escape' => TRUE)
+					: array('field' => trim($field), 'direction' => $direction, 'escape' => TRUE);
+			}
 		}
 
-		$this->qb_orderby[] = $orderby_statement = $orderby.$direction;
-
+		$this->qb_orderby = array_merge($this->qb_orderby, $qb_orderby);
 		if ($this->qb_caching === TRUE)
 		{
-			$this->qb_cache_orderby[] = $orderby_statement;
+			$this->qb_cache_orderby = array_merge($this->qb_cache_orderby, $qb_orderby);
 			$this->qb_cache_exists[] = 'orderby';
 		}
 
@@ -1044,7 +1014,7 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	 * @param	int	the offset value
 	 * @return	object
 	 */
-	public function limit($value, $offset = NULL)
+	public function limit($value, $offset = FALSE)
 	{
 		is_null($value) OR $this->qb_limit = (int) $value;
 		empty($offset) OR $this->qb_offset = (int) $offset;
@@ -1074,13 +1044,11 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	 * Generates a platform-specific LIMIT clause
 	 *
 	 * @param	string	the sql query string
-	 * @param	int	the number of rows to limit the query to
-	 * @param	int	the offset value
 	 * @return	string
 	 */
-	protected function _limit($sql, $limit, $offset)
+	protected function _limit($sql)
 	{
-		return $sql.' LIMIT '.($offset ? $offset.', ' : '').$limit;
+		return $sql.' LIMIT '.($this->qb_offset ? $this->qb_offset.', ' : '').$this->qb_limit;
 	}
 
 	// --------------------------------------------------------------------
@@ -1213,9 +1181,10 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	 *
 	 * Allows the where clause, limit and offset to be added directly
 	 *
-	 * @param	string	the where clause
-	 * @param	string	the limit clause
-	 * @param	string	the offset clause
+	 * @param	string	$table = ''
+	 * @param	string	$where = NULL
+	 * @param	int	$limit = NULL
+	 * @param	int	$offset = NULL
 	 * @return	object
 	 */
 	public function get_where($table = '', $where = NULL, $limit = NULL, $offset = NULL)
@@ -1247,9 +1216,9 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	 *
 	 * Compiles batch insert strings and runs the queries
 	 *
-	 * @param	string	the table to retrieve the results from
-	 * @param	array	an associative array of insert values
-	 * @return	object
+	 * @param	string	$table = ''	table to insert into
+	 * @param	array	$set 		an associative array of insert values
+	 * @return	int	number of rows inserted or FALSE on failure
 	 */
 	public function insert_batch($table = '', $set = NULL)
 	{
@@ -1260,12 +1229,8 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 
 		if (count($this->qb_set) === 0)
 		{
-			if ($this->db_debug)
-			{
-				// No valid data array. Folds in cases where keys and values did not match up
-				return $this->display_error('db_must_use_set');
-			}
-			return FALSE;
+			// No valid data array. Folds in cases where keys and values did not match up
+			return ($this->db_debug) ? $this->display_error('db_must_use_set') : FALSE;
 		}
 
 		if ($table === '')
@@ -1279,13 +1244,15 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 		}
 
 		// Batch this baby
+		$affected_rows = 0;
 		for ($i = 0, $total = count($this->qb_set); $i < $total; $i += 100)
 		{
 			$this->query($this->_insert_batch($this->protect_identifiers($table, TRUE, NULL, FALSE), $this->qb_keys, array_slice($this->qb_set, $i, 100)));
+			$affected_rows += $this->affected_rows();
 		}
 
 		$this->_reset_write();
-		return TRUE;
+		return $affected_rows;
 	}
 
 	// --------------------------------------------------------------------
@@ -1522,19 +1489,18 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	// --------------------------------------------------------------------
 
 	/**
-	 * From Tables
+	 * FROM tables
+	 *
+	 * Groups tables in FROM clauses if needed, so there is no confusion
+	 * about operator precedence.
 	 *
-	 * This public function implicitly groups FROM tables so there is no confusion
-	 * about operator precedence in harmony with SQL standards
+	 * Note: This is only used (and overriden) by MySQL and CUBRID.
 	 *
-	 * @param       array
-	 * @return      string
+	 * @return	string
 	 */
-	protected function _from_tables($tables)
+	protected function _from_tables()
 	{
-		is_array($tables) OR $tables = array($tables);
-
-		return (count($tables) === 1) ? $tables[0] : '('.implode(', ', $tables).')';
+		return implode(', ', $this->qb_from);
 	}
 
 	// --------------------------------------------------------------------
@@ -1558,7 +1524,7 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 			return FALSE;
 		}
 
-		$sql = $this->_update($this->protect_identifiers($this->qb_from[0], TRUE, NULL, FALSE), $this->qb_set, $this->qb_where, $this->qb_orderby, $this->qb_limit);
+		$sql = $this->_update($this->protect_identifiers($this->qb_from[0], TRUE, NULL, FALSE), $this->qb_set);
 
 		if ($reset === TRUE)
 		{
@@ -1575,9 +1541,10 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	 *
 	 * Compiles an update string and runs the query
 	 *
-	 * @param	string	the table to retrieve the results from
-	 * @param	array	an associative array of update values
-	 * @param	mixed	the where clause
+	 * @param	string	$table = ''
+	 * @param	array	$set = NULL	an associative array of update values
+	 * @param	mixed	$where = NULL
+	 * @param	int	$limit = NULL
 	 * @return	object
 	 */
 	public function update($table = '', $set = NULL, $where = NULL, $limit = NULL)
@@ -1605,7 +1572,7 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 			$this->limit($limit);
 		}
 
-		$sql = $this->_update($this->protect_identifiers($this->qb_from[0], TRUE, NULL, FALSE), $this->qb_set, $this->qb_where, $this->qb_orderby, $this->qb_limit, $this->qb_like);
+		$sql = $this->_update($this->protect_identifiers($this->qb_from[0], TRUE, NULL, FALSE), $this->qb_set);
 
 		$this->_reset_write();
 		return $this->query($sql);
@@ -1652,7 +1619,7 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	 * @param	string	the table to retrieve the results from
 	 * @param	array	an associative array of update values
 	 * @param	string	the where key
-	 * @return	bool
+	 * @return	int	number of rows affected or FALSE on failure
 	 */
 	public function update_batch($table = '', $set = NULL, $index = NULL)
 	{
@@ -1685,13 +1652,15 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 		}
 
 		// Batch this baby
+		$affected_rows = 0;
 		for ($i = 0, $total = count($this->qb_set); $i < $total; $i += 100)
 		{
-			$this->query($this->_update_batch($this->protect_identifiers($table, TRUE, NULL, FALSE), array_slice($this->qb_set, $i, 100), $this->protect_identifiers($index), $this->qb_where));
+			$this->query($this->_update_batch($this->protect_identifiers($table, TRUE, NULL, FALSE), array_slice($this->qb_set, $i, 100), $this->protect_identifiers($index)));
+			$affected_rows += $this->affected_rows();
 		}
 
 		$this->_reset_write();
-		return TRUE;
+		return $affected_rows;
 	}
 
 	// --------------------------------------------------------------------
@@ -1852,7 +1821,7 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	 * @param	mixed	the where clause
 	 * @param	mixed	the limit clause
 	 * @param	bool
-	 * @return	object
+	 * @return	mixed
 	 */
 	public function delete($table = '', $where = '', $limit = NULL, $reset_data = TRUE)
 	{
@@ -1872,10 +1841,8 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 		{
 			foreach ($table as $single_table)
 			{
-				$this->delete($single_table, $where, $limit, FALSE);
+				$this->delete($single_table, $where, $limit, $reset_data);
 			}
-
-			$this->_reset_write();
 			return;
 		}
 		else
@@ -1893,12 +1860,12 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 			$this->limit($limit);
 		}
 
-		if (count($this->qb_where) === 0 && count($this->qb_wherein) === 0 && count($this->qb_like) === 0)
+		if (count($this->qb_where) === 0)
 		{
 			return ($this->db_debug) ? $this->display_error('db_del_must_use_where') : FALSE;
 		}
 
-		$sql = $this->_delete($table, $this->qb_where, $this->qb_like, $this->qb_limit);
+		$sql = $this->_delete($table);
 		if ($reset_data)
 		{
 			$this->_reset_write();
@@ -1915,21 +1882,12 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	 * Generates a platform-specific delete string from the supplied data
 	 *
 	 * @param	string	the table name
-	 * @param	array	the where clause
-	 * @param	array	the like clause
-	 * @param	string	the limit clause
 	 * @return	string
 	 */
-	protected function _delete($table, $where = array(), $like = array(), $limit = FALSE)
+	protected function _delete($table)
 	{
-		$conditions = array();
-
-		empty($where) OR $conditions[] = implode(' ', $where);
-		empty($like) OR $conditions[] = implode(' ', $like);
-
-		return 'DELETE FROM '.$table
-			.(count($conditions) > 0 ? ' WHERE '.implode(' AND ', $conditions) : '')
-			.($limit ? ' LIMIT '.(int) $limit : '');
+		return 'DELETE FROM '.$table.$this->_compile_wh('qb_where')
+			.($this->qb_limit ? ' LIMIT '.$this->qb_limit : '');
 	}
 
 	// --------------------------------------------------------------------
@@ -2018,8 +1976,9 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	 * Compile the SELECT statement
 	 *
 	 * Generates a query string based on which functions were used.
-	 * Should not be called directly.  The get() function calls it.
+	 * Should not be called directly.
 	 *
+	 * @param	bool	$select_override = FALSE
 	 * @return	string
 	 */
 	protected function _compile_select($select_override = FALSE)
@@ -2058,7 +2017,7 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 		// Write the "FROM" portion of the query
 		if (count($this->qb_from) > 0)
 		{
-			$sql .= "\nFROM ".$this->_from_tables($this->qb_from);
+			$sql .= "\nFROM ".$this->_from_tables();
 		}
 
 		// Write the "JOIN" portion of the query
@@ -2067,50 +2026,156 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 			$sql .= "\n".implode("\n", $this->qb_join);
 		}
 
-		// Write the "WHERE" portion of the query
-		if (count($this->qb_where) > 0 OR count($this->qb_like) > 0)
+		$sql .= $this->_compile_wh('qb_where')
+			.$this->_compile_group_by()
+			.$this->_compile_wh('qb_having')
+			.$this->_compile_order_by(); // ORDER BY
+
+		// LIMIT
+		if ($this->qb_limit)
 		{
-			$sql .= "\nWHERE ";
+			return $this->_limit($sql."\n");
 		}
 
-		$sql .= implode("\n", $this->qb_where);
+		return $sql;
+	}
+
+	// --------------------------------------------------------------------
 
-		// Write the "LIKE" portion of the query
-		if (count($this->qb_like) > 0)
+	/**
+	 * Compile WHERE, HAVING statements
+	 *
+	 * Escapes identifiers in WHERE and HAVING statements at execution time.
+	 *
+	 * Required so that aliases are tracked properly, regardless of wether
+	 * where(), or_where(), having(), or_having are called prior to from(),
+	 * join() and dbprefix is added only if needed.
+	 *
+	 * @param	string	'qb_where' or 'qb_having'
+	 * @return	string	SQL statement
+	 */
+	protected function _compile_wh($qb_key)
+	{
+		if (count($this->$qb_key) > 0)
 		{
-			if (count($this->qb_where) > 0)
+			for ($i = 0, $c = count($this->$qb_key); $i < $c; $i++)
 			{
-				$sql .= "\nAND ";
+				if ($this->{$qb_key}[$i]['escape'] === FALSE)
+				{
+					$this->{$qb_key}[$i] = $this->{$qb_key}[$i]['condition'];
+					continue;
+				}
+
+				// Split multiple conditions
+				$conditions = preg_split(
+					'/(\s*AND\s+|\s*OR\s+)/i',
+					$this->{$qb_key}[$i]['condition'],
+					-1,
+					PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY
+				);
+
+				for ($ci = 0, $cc = count($conditions); $ci < $cc; $ci++)
+				{
+					if (($op = $this->_get_operator($conditions[$ci])) === FALSE
+						OR ! preg_match('/^(\(?)(.*)('.preg_quote($op).')\s*(.*(?<!\)))?(\)?)$/i', $conditions[$ci], $matches))
+					{
+						continue;
+					}
+
+					// $matches = array(
+					//	0 => '(test <= foo)',	/* the whole thing */
+					//	1 => '(',		/* optional */
+					//	2 => 'test',		/* the field name */
+					//	3 => ' <= ',		/* $op */
+					//	4 => 'foo',		/* optional, if $op is e.g. 'IS NULL' */
+					//	5 => ')'		/* optional */
+					// );
+
+					if ( ! empty($matches[4]))
+					{
+						$this->_is_literal($matches[4]) OR $matches[4] = $this->protect_identifiers(trim($matches[4]));
+						$matches[4] = ' '.$matches[4];
+					}
+
+					$conditions[$ci] = $matches[1].$this->protect_identifiers(trim($matches[2]))
+						.' '.trim($matches[3]).$matches[4].$matches[5];
+				}
+
+				$this->{$qb_key}[$i] = implode('', $conditions);
 			}
 
-			$sql .= implode("\n", $this->qb_like);
+			return ($qb_key === 'qb_having' ? "\nHAVING " : "\nWHERE ")
+				.implode("\n", $this->$qb_key);
 		}
 
-		// Write the "GROUP BY" portion of the query
+		return '';
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Compile GROUP BY
+	 *
+	 * Escapes identifiers in GROUP BY statements at execution time.
+	 *
+	 * Required so that aliases are tracked properly, regardless of wether
+	 * group_by() is called prior to from(), join() and dbprefix is added
+	 * only if needed.
+	 *
+	 * @return	string	SQL statement
+	 */
+	protected function _compile_group_by()
+	{
 		if (count($this->qb_groupby) > 0)
 		{
-			$sql .= "\nGROUP BY ".implode(', ', $this->qb_groupby);
-		}
+			for ($i = 0, $c = count($this->qb_groupby); $i < $c; $i++)
+			{
+				$this->qb_groupby[$i] = ($this->qb_groupby[$i]['escape'] === FALSE OR $this->_is_literal($this->qb_groupby[$i]['field']))
+					? $this->qb_groupby[$i]['field']
+					: $this->protect_identifiers($this->qb_groupby[$i]['field']);
+			}
 
-		// Write the "HAVING" portion of the query
-		if (count($this->qb_having) > 0)
-		{
-			$sql .= "\nHAVING ".implode("\n", $this->qb_having);
+			return "\nGROUP BY ".implode(', ', $this->qb_groupby);
 		}
 
-		// Write the "ORDER BY" portion of the query
-		if (count($this->qb_orderby) > 0)
+		return '';
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Compile ORDER BY
+	 *
+	 * Escapes identifiers in ORDER BY statements at execution time.
+	 *
+	 * Required so that aliases are tracked properly, regardless of wether
+	 * order_by() is called prior to from(), join() and dbprefix is added
+	 * only if needed.
+	 *
+	 * @return	string	SQL statement
+	 */
+	protected function _compile_order_by()
+	{
+		if (is_array($this->qb_orderby) && count($this->qb_orderby) > 0)
 		{
-			$sql .= "\nORDER BY ".implode(', ', $this->qb_orderby);
-		}
+			for ($i = 0, $c = count($this->qb_orderby); $i < $c; $i++)
+			{
+				if ($this->qb_orderby[$i]['escape'] !== FALSE && ! $this->_is_literal($this->qb_orderby[$i]['field']))
+				{
+					$this->qb_orderby[$i]['field'] = $this->protect_identifiers($this->qb_orderby[$i]['field']);
+				}
+
+				$this->qb_orderby[$i] = $this->qb_orderby[$i]['field'].$this->qb_orderby[$i]['direction'];
+			}
 
-		// Write the "LIMIT" portion of the query
-		if (is_numeric($this->qb_limit))
+			return $this->qb_orderby = "\nORDER BY ".implode(', ', $this->qb_orderby);
+		}
+		elseif (is_string($this->qb_orderby))
 		{
-			return $this->_limit($sql."\n", $this->qb_limit, $this->qb_offset);
+			return $this->qb_orderby;
 		}
 
-		return $sql;
+		return '';
 	}
 
 	// --------------------------------------------------------------------
@@ -2277,6 +2342,36 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	// --------------------------------------------------------------------
 
 	/**
+	 * Is literal
+	 *
+	 * Determines if a string represents a literal value or a field name
+	 *
+	 * @param	string
+	 * @return	bool
+	 */
+	protected function _is_literal($str)
+	{
+		$str = trim($str);
+
+		if (empty($str))
+		{
+			return TRUE;
+		}
+
+		static $_str;
+
+		if (empty($_str))
+		{
+			$_str = ($this->_escape_char !== '"')
+				? array('"', "'") : array("'");
+		}
+
+		return (ctype_digit($str) OR in_array($str[0], $_str, TRUE));
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
 	 * Reset Query Builder values.
 	 *
 	 * Publicly-visible method to reset the QB values.
@@ -2322,11 +2417,9 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 					'qb_from'		=> array(),
 					'qb_join'		=> array(),
 					'qb_where'		=> array(),
-					'qb_like'		=> array(),
 					'qb_groupby'		=> array(),
 					'qb_having'		=> array(),
 					'qb_orderby'		=> array(),
-					'qb_wherein'		=> array(),
 					'qb_aliased_tables'	=> array(),
 					'qb_no_escape'		=> array(),
 					'qb_distinct'		=> FALSE,
@@ -2351,7 +2444,6 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 			'qb_set'	=> array(),
 			'qb_from'	=> array(),
 			'qb_where'	=> array(),
-			'qb_like'	=> array(),
 			'qb_orderby'	=> array(),
 			'qb_keys'	=> array(),
 			'qb_limit'	=> FALSE
diff --git a/system/database/DB_result.php b/system/database/DB_result.php
index d44df6c02..76093f918 100644
--- a/system/database/DB_result.php
+++ b/system/database/DB_result.php
@@ -251,27 +251,24 @@ class CI_DB_result {
 	/**
 	 * Query result.  Acts as a wrapper function for the following functions.
 	 *
-	 * @param	string
-	 * @param	string	can be "object" or "array"
-	 * @return	mixed	either a result object or array
+	 * @param	mixed	$n = 0
+	 * @param	string	$type = 'object'	'object' or 'array'
+	 * @return	mixed
 	 */
 	public function row($n = 0, $type = 'object')
 	{
 		if ( ! is_numeric($n))
 		{
 			// We cache the row data for subsequent uses
-			if ( ! is_array($this->row_data))
-			{
-				$this->row_data = $this->row_array(0);
-			}
+			is_array($this->row_data) OR $this->row_data = $this->row_array(0);
 
-			// array_key_exists() instead of isset() to allow for MySQL NULL values
-			if (array_key_exists($n, $this->row_data))
+			// array_key_exists() instead of isset() to allow for NULL values
+			if (empty($this->row_data) OR ! array_key_exists($n, $this->row_data))
 			{
-				return $this->row_data[$n];
+				return NULL;
 			}
-			// reset the $n variable if the result was not achieved
-			$n = 0;
+
+			return $this->row_data[$n];
 		}
 
 		if ($type === 'object') return $this->row_object($n);
@@ -284,6 +281,8 @@ class CI_DB_result {
 	/**
 	 * Assigns an item into a particular column slot
 	 *
+	 * @param	mixed	$key
+	 * @param	mixed	$value
 	 * @return	void
 	 */
 	public function set_row($key, $value = NULL)
@@ -314,6 +313,8 @@ class CI_DB_result {
 	/**
 	 * Returns a single result row - custom object version
 	 *
+	 * @param	int	$n
+	 * @param	string	$type
 	 * @return	object
 	 */
 	public function custom_row_object($n, $type)
@@ -338,6 +339,7 @@ class CI_DB_result {
 	/**
 	 * Returns a single result row - object version
 	 *
+	 * @param	int	$n = 0
 	 * @return	object
 	 */
 	public function row_object($n = 0)
@@ -361,6 +363,7 @@ class CI_DB_result {
 	/**
 	 * Returns a single result row - array version
 	 *
+	 * @param	int	$n = 0
 	 * @return	array
 	 */
 	public function row_array($n = 0)
@@ -384,7 +387,8 @@ class CI_DB_result {
 	/**
 	 * Returns the "first" row
 	 *
-	 * @return	object
+	 * @param	string	$type = 'object'
+	 * @return	mixed
 	 */
 	public function first_row($type = 'object')
 	{
@@ -397,7 +401,8 @@ class CI_DB_result {
 	/**
 	 * Returns the "last" row
 	 *
-	 * @return	object
+	 * @param	string	$type = 'object'
+	 * @return	mixed
 	 */
 	public function last_row($type = 'object')
 	{
@@ -410,7 +415,8 @@ class CI_DB_result {
 	/**
 	 * Returns the "next" row
 	 *
-	 * @return	object
+	 * @param	string	$type = 'object'
+	 * @return	mixed
 	 */
 	public function next_row($type = 'object')
 	{
@@ -433,7 +439,8 @@ class CI_DB_result {
 	/**
 	 * Returns the "previous" row
 	 *
-	 * @return	object
+	 * @param	string	$type = 'object'
+	 * @return	mixed
 	 */
 	public function previous_row($type = 'object')
 	{
@@ -455,8 +462,8 @@ class CI_DB_result {
 	/**
 	 * Returns an unbuffered row and move pointer to next row
 	 *
-	 * @param	string	'array', 'object' or a custom class name
-	 * @return	mixed	either a result object or array
+	 * @param	string	$type = 'object'	'array', 'object' or a custom class name
+	 * @return	mixed
 	 */
 	public function unbuffered_row($type = 'object')
 	{
diff --git a/system/database/DB_utility.php b/system/database/DB_utility.php
index 6a3b40779..8078e2bf6 100644
--- a/system/database/DB_utility.php
+++ b/system/database/DB_utility.php
@@ -41,6 +41,11 @@ abstract class CI_DB_utility extends CI_DB_forge {
 	protected $_optimize_table	= FALSE;
 	protected $_repair_table	= FALSE;
 
+	/**
+	 * Constructor
+	 *
+	 * @return	void
+	 */
 	public function __construct()
 	{
 		// Assign the main database object to $this->db
@@ -275,6 +280,7 @@ abstract class CI_DB_utility extends CI_DB_forge {
 	/**
 	 * Database Backup
 	 *
+	 * @param	array	$params = array()
 	 * @return	void
 	 */
 	public function backup($params = array())
diff --git a/system/database/drivers/cubrid/cubrid_driver.php b/system/database/drivers/cubrid/cubrid_driver.php
index a3d0287f5..8e77d8396 100644
--- a/system/database/drivers/cubrid/cubrid_driver.php
+++ b/system/database/drivers/cubrid/cubrid_driver.php
@@ -45,15 +45,17 @@ class CI_DB_cubrid_driver extends CI_DB {
 	// The character used for escaping - no need in CUBRID
 	protected $_escape_char = '`';
 
-	// clause and character used for LIKE escape sequences - not used in CUBRID
-	protected $_like_escape_str = '';
-	protected $_like_escape_chr = '';
-
 	protected $_random_keyword = ' RAND()'; // database specific random keyword
 
 	// CUBRID-specific properties
 	public $auto_commit = TRUE;
 
+	/**
+	 * Constructor
+	 *
+	 * @param	array	$params
+	 * @return	void
+	 */
 	public function __construct($params)
 	{
 		parent::__construct($params);
@@ -72,6 +74,8 @@ class CI_DB_cubrid_driver extends CI_DB {
 		}
 	}
 
+	// --------------------------------------------------------------------
+
 	/**
 	 * Non-persistent database connection
 	 *
@@ -182,6 +186,7 @@ class CI_DB_cubrid_driver extends CI_DB {
 	/**
 	 * Begin Transaction
 	 *
+	 * @param	bool	$test_mode = FALSE
 	 * @return	bool
 	 */
 	public function trans_begin($test_mode = FALSE)
@@ -396,10 +401,10 @@ class CI_DB_cubrid_driver extends CI_DB {
 	 *
 	 * @param	string	the table name
 	 * @param	array	the update data
-	 * @param	array	the where clause
+	 * @param	string	the where key
 	 * @return	string
 	 */
-	protected function _update_batch($table, $values, $index, $where = NULL)
+	protected function _update_batch($table, $values, $index)
 	{
 		$ids = array();
 		foreach ($values as $key => $val)
@@ -423,9 +428,29 @@ class CI_DB_cubrid_driver extends CI_DB {
 				.'ELSE '.$k.' END, ';
 		}
 
-		return 'UPDATE '.$table.' SET '.substr($cases, 0, -2)
-			.' WHERE '.(($where !== '' && count($where) > 0) ? implode(' ', $where).' AND ' : '')
-			.$index.' IN ('.implode(',', $ids).')';
+		$this->where($index.' IN('.implode(',', $ids).')', NULL, FALSE);
+
+		return 'UPDATE '.$table.' SET '.substr($cases, 0, -2).$this->_compile_wh('qb_where');
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * FROM tables
+	 *
+	 * Groups tables in FROM clauses if needed, so there is no confusion
+	 * about operator precedence.
+	 *
+	 * @return	string
+	 */
+	protected function _from_tables()
+	{
+		if ( ! empty($this->qb_join) && count($this->qb_from) > 1)
+		{
+			return '('.implode(', ', $this->qb_from).')';
+		}
+
+		return implode(', ', $this->qb_from);
 	}
 
 	// --------------------------------------------------------------------
diff --git a/system/database/drivers/cubrid/cubrid_result.php b/system/database/drivers/cubrid/cubrid_result.php
index 4a06a2d39..360c50dc2 100644
--- a/system/database/drivers/cubrid/cubrid_result.php
+++ b/system/database/drivers/cubrid/cubrid_result.php
@@ -132,6 +132,7 @@ class CI_DB_cubrid_result extends CI_DB_result {
 	 * this internally before fetching results to make sure the
 	 * result set starts at zero
 	 *
+	 * @param	int	$n = 0
 	 * @return	bool
 	 */
 	protected function _data_seek($n = 0)
diff --git a/system/database/drivers/ibase/ibase_driver.php b/system/database/drivers/ibase/ibase_driver.php
index c9027670d..c3be519bf 100644
--- a/system/database/drivers/ibase/ibase_driver.php
+++ b/system/database/drivers/ibase/ibase_driver.php
@@ -45,10 +45,6 @@ class CI_DB_ibase_driver extends CI_DB {
 	// The character used to escape with
 	protected $_escape_char = '"';
 
-	// clause and character used for LIKE escape sequences
-	protected $_like_escape_str = " ESCAPE '%s' ";
-	protected $_like_escape_chr = '!';
-
 	protected $_random_keyword = ' Random()'; // database specific random keyword
 
 	// Keeps track of the resource for the current transaction
@@ -120,6 +116,7 @@ class CI_DB_ibase_driver extends CI_DB {
 	/**
 	 * Begin Transaction
 	 *
+	 * @param	bool	$test_mode = FALSE
 	 * @return	bool
 	 */
 	public function trans_begin($test_mode = FALSE)
@@ -285,7 +282,10 @@ class CI_DB_ibase_driver extends CI_DB {
 	 */
 	protected function _field_data($table)
 	{
-		return $this->_limit('SELECT * FROM '.$this->protect_identifiers($table), 1, NULL);
+		$this->qb_limit = 1;
+		$sql = $this->_limit('SELECT * FROM '.$this->protect_identifiers($table));
+		$this->qb_limit = 0;
+		return $sql;
 	}
 
 	// --------------------------------------------------------------------
@@ -306,51 +306,18 @@ class CI_DB_ibase_driver extends CI_DB {
 	// --------------------------------------------------------------------
 
 	/**
-	 * From Tables
-	 *
-	 * This public 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, $like = array())
+	protected function _update($table, $values)
 	{
-		foreach ($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) : '');
+		$this->qb_limit = FALSE;
+		return parent::_update($table, $values);
 	}
 
 	// --------------------------------------------------------------------
@@ -379,19 +346,12 @@ class CI_DB_ibase_driver extends CI_DB {
 	 * 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(), $limit = FALSE)
+	protected function _delete($table)
 	{
-		$conditions = array();
-
-		empty($where) OR $conditions[] = implode(' ', $where);
-		empty($like) OR $conditions[] = implode(' ', $like);
-
-		return 'DELETE FROM '.$table.(count($conditions) > 0 ? ' WHERE '.implode(' AND ', $conditions) : '');
+		$this->qb_limit = FALSE;
+		return parent::_delete($table);
 	}
 
 	// --------------------------------------------------------------------
@@ -402,22 +362,20 @@ class CI_DB_ibase_driver extends CI_DB {
 	 * 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, $offset)
+	protected function _limit($sql)
 	{
 		// Limit clause depends on if Interbase or Firebird
 		if (stripos($this->version(), 'firebird') !== FALSE)
 		{
-			$select = 'FIRST '. (int) $limit
-				.($offset ? ' SKIP '. (int) $offset : '');
+			$select = 'FIRST '.$this->qb_limit
+				.($this->qb_offset ? ' SKIP '.$this->qb_offset : '');
 		}
 		else
 		{
 			$select = 'ROWS '
-				.($offset ? (int) $offset.' TO '.($limit + $offset) : (int) $limit);
+				.($this->qb_offset ? $this->qb_offset.' TO '.($this->qb_limit + $this->qb_offset) : $this->qb_limit);
 		}
 
 		return preg_replace('`SELECT`i', 'SELECT '.$select, $sql);
diff --git a/system/database/drivers/mssql/mssql_driver.php b/system/database/drivers/mssql/mssql_driver.php
index 1714704a8..2063dad90 100644
--- a/system/database/drivers/mssql/mssql_driver.php
+++ b/system/database/drivers/mssql/mssql_driver.php
@@ -45,21 +45,17 @@ class CI_DB_mssql_driver extends CI_DB {
 	// The character used for escaping
 	protected $_escape_char = '"';
 
-	// clause and character used for LIKE escape sequences
-	protected $_like_escape_str = " ESCAPE '%s' ";
-	protected $_like_escape_chr = '!';
-
 	protected $_random_keyword = ' NEWID()';
 
 	// MSSQL-specific properties
 	protected $_quoted_identifier = TRUE;
 
-	/*
+	/**
 	 * Constructor
 	 *
 	 * Appends the port number to the hostname, if needed.
 	 *
-	 * @param	array
+	 * @param	array	$params
 	 * @return	void
 	 */
 	public function __construct($params)
@@ -156,6 +152,7 @@ class CI_DB_mssql_driver extends CI_DB {
 	/**
 	 * Begin Transaction
 	 *
+	 * @param	bool	$test_mode = FALSE
 	 * @return	bool
 	 */
 	public function trans_begin($test_mode = FALSE)
@@ -366,49 +363,19 @@ class CI_DB_mssql_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($tables)
-	{
-		return is_array($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, $like = array())
+	protected function _update($table, $values)
 	{
-		foreach($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(', ', $valstr).' WHERE '.$where;
+		$this->qb_limit = FALSE;
+		$this->qb_orderby = array();
+		return parent::_update($table, $values);
 	}
 
 	// --------------------------------------------------------------------
@@ -437,23 +404,16 @@ class CI_DB_mssql_driver extends CI_DB {
 	 * 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(), $limit = FALSE)
+	protected function _delete($table)
 	{
-		$conditions = array();
-
-		empty($where) OR $conditions[] = implode(' ', $where);
-		empty($like) OR $conditions[] = implode(' ', $like);
-
-		$conditions = (count($conditions) > 0) ? ' WHERE '.implode(' AND ', $conditions) : '';
+		if ($this->qb_limit)
+		{
+			return 'WITH ci_delete AS (SELECT TOP '.$this->qb_limit.' * FROM '.$table.$this->_compile_wh('qb_where').') DELETE FROM ci_delete';
+		}
 
-		return ($limit)
-			? 'WITH ci_delete AS (SELECT TOP '.$limit.' * FROM '.$table.$conditions.') DELETE FROM ci_delete'
-			: 'DELETE FROM '.$table.$conditions;
+		return parent::_delete($table);
 	}
 
 	// --------------------------------------------------------------------
@@ -464,33 +424,44 @@ class CI_DB_mssql_driver extends CI_DB {
 	 * 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, $offset)
+	protected function _limit($sql)
 	{
-		// 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;
+		$limit = $this->qb_offset + $this->qb_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))
+		if (version_compare($this->version(), '9', '>=') && $this->qb_offset && ! empty($this->qb_orderby))
 		{
-			$orderby = 'ORDER BY '.implode(', ', $this->qb_orderby);
+			$orderby = $this->_compile_order_by();
 
 			// We have to strip the ORDER BY clause
-			$sql = trim(substr($sql, 0, strrpos($sql, 'ORDER BY '.$orderby)));
+			$sql = trim(substr($sql, 0, strrpos($sql, $orderby)));
+
+			// Get the fields to select from our subquery, so that we can avoid CI_rownum appearing in the actual results
+			if (count($this->qb_select) === 0)
+			{
+				$select = '*'; // Inevitable
+			}
+			else
+			{
+				// Use only field names and their aliases, everything else is out of our scope.
+				$select = array();
+				$field_regexp = ($this->_quoted_identifier)
+					? '("[^\"]+")' : '(\[[^\]]+\])';
+				for ($i = 0, $c = count($this->qb_select); $i < $c; $i++)
+				{
+					$select[] = preg_match('/(?:\s|\.)'.$field_regexp.'$/i', $this->qb_select[$i], $m)
+						? $m[1] : $this->qb_select[$i];
+				}
+				$select = implode(', ', $select);
+			}
 
-			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 'SELECT '.$select." FROM (\n\n"
+				.preg_replace('/^(SELECT( DISTINCT)?)/i', '\\1 ROW_NUMBER() OVER('.trim($orderby).') AS '.$this->escape_identifiers('CI_rownum').', ', $sql)
+				."\n\n) ".$this->escape_identifiers('CI_subquery')
+				."\nWHERE ".$this->escape_identifiers('CI_rownum').' BETWEEN '.($this->qb_offset + 1).' AND '.$limit;
 		}
 
 		return preg_replace('/(^\SELECT (DISTINCT)?)/i','\\1 TOP '.$limit.' ', $sql);
diff --git a/system/database/drivers/mssql/mssql_result.php b/system/database/drivers/mssql/mssql_result.php
index aeede3f4b..84d2814f1 100644
--- a/system/database/drivers/mssql/mssql_result.php
+++ b/system/database/drivers/mssql/mssql_result.php
@@ -133,6 +133,7 @@ class CI_DB_mssql_result extends CI_DB_result {
 	 * this internally before fetching results to make sure the
 	 * result set starts at zero
 	 *
+	 * @param	int	$n = 0
 	 * @return	bool
 	 */
 	protected function _data_seek($n = 0)
diff --git a/system/database/drivers/mysql/mysql_driver.php b/system/database/drivers/mysql/mysql_driver.php
index 29db90408..f82e775e6 100644
--- a/system/database/drivers/mysql/mysql_driver.php
+++ b/system/database/drivers/mysql/mysql_driver.php
@@ -41,14 +41,11 @@
 class CI_DB_mysql_driver extends CI_DB {
 
 	public $dbdriver = 'mysql';
+	public $compress = FALSE;
 
 	// The character used for escaping
 	protected $_escape_char = '`';
 
-	// clause and character used for LIKE escape sequences - not used in MySQL
-	protected $_like_escape_str = '';
-	protected $_like_escape_chr = '\\';
-
 	protected $_random_keyword = ' RAND()'; // database specific random keyword
 
 	/**
@@ -79,11 +76,21 @@ class CI_DB_mysql_driver extends CI_DB {
 	/**
 	 * Non-persistent database connection
 	 *
+	 * @param	bool
 	 * @return	resource
 	 */
-	public function db_connect()
+	public function db_connect($persistent = FALSE)
 	{
-		return @mysql_connect($this->hostname, $this->username, $this->password, TRUE);
+		$client_flags = ($this->compress === FALSE) ? 0 : MYSQL_CLIENT_COMPRESS;
+
+		if ($this->encrypt === TRUE)
+		{
+			$client_flags = $client_flags | MYSQL_CLIENT_SSL;
+		}
+
+		return ($persistent === TRUE)
+			? @mysql_pconnect($this->hostname, $this->username, $this->password, $client_flags)
+			: @mysql_connect($this->hostname, $this->username, $this->password, TRUE, $client_flags);
 	}
 
 	// --------------------------------------------------------------------
@@ -95,7 +102,7 @@ class CI_DB_mysql_driver extends CI_DB {
 	 */
 	public function db_pconnect()
 	{
-		return @mysql_pconnect($this->hostname, $this->username, $this->password);
+		return $this->db_connect(TRUE);
 	}
 
 	// --------------------------------------------------------------------
@@ -207,6 +214,7 @@ class CI_DB_mysql_driver extends CI_DB {
 	/**
 	 * Begin Transaction
 	 *
+	 * @param	bool	$test_mode = FALSE
 	 * @return	bool
 	 */
 	public function trans_begin($test_mode = FALSE)
@@ -420,10 +428,10 @@ class CI_DB_mysql_driver extends CI_DB {
 	 *
 	 * @param	string	the table name
 	 * @param	array	the update data
-	 * @param	array	the where clause
+	 * @param	string	the where key
 	 * @return	string
 	 */
-	protected function _update_batch($table, $values, $index, $where = NULL)
+	protected function _update_batch($table, $values, $index)
 	{
 		$ids = array();
 		foreach ($values as $key => $val)
@@ -447,9 +455,29 @@ class CI_DB_mysql_driver extends CI_DB {
 				.'ELSE '.$k.' END, ';
 		}
 
-		return 'UPDATE '.$table.' SET '.substr($cases, 0, -2)
-			.' WHERE '.(($where !== '' && count($where) > 0) ? implode(' ', $where).' AND ' : '')
-			.$index.' IN('.implode(',', $ids).')';
+		$this->where($index.' IN('.implode(',', $ids).')', NULL, FALSE);
+
+		return 'UPDATE '.$table.' SET '.substr($cases, 0, -2).$this->_compile_wh('qb_where');
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * FROM tables
+	 *
+	 * Groups tables in FROM clauses if needed, so there is no confusion
+	 * about operator precedence.
+	 *
+	 * @return	string
+	 */
+	protected function _from_tables()
+	{
+		if ( ! empty($this->qb_join) && count($this->qb_from) > 1)
+		{
+			return '('.implode(', ', $this->qb_from).')';
+		}
+
+		return implode(', ', $this->qb_from);
 	}
 
 	// --------------------------------------------------------------------
diff --git a/system/database/drivers/mysql/mysql_result.php b/system/database/drivers/mysql/mysql_result.php
index 7fbb65496..b3f669e40 100644
--- a/system/database/drivers/mysql/mysql_result.php
+++ b/system/database/drivers/mysql/mysql_result.php
@@ -146,6 +146,7 @@ class CI_DB_mysql_result extends CI_DB_result {
 	 * this internally before fetching results to make sure the
 	 * result set starts at zero
 	 *
+	 * @param	int	$n = 0
 	 * @return	bool
 	 */
 	protected function _data_seek($n = 0)
diff --git a/system/database/drivers/mysqli/mysqli_driver.php b/system/database/drivers/mysqli/mysqli_driver.php
index be61aab20..6c4f87513 100644
--- a/system/database/drivers/mysqli/mysqli_driver.php
+++ b/system/database/drivers/mysqli/mysqli_driver.php
@@ -41,14 +41,11 @@
 class CI_DB_mysqli_driver extends CI_DB {
 
 	public $dbdriver = 'mysqli';
+	public $compress = FALSE;
 
 	// The character used for escaping
 	protected $_escape_char = '`';
 
-	// clause and character used for LIKE escape sequences - not used in MySQL
-	protected $_like_escape_str = '';
-	protected $_like_escape_chr = '\\';
-
 	protected $_random_keyword = ' RAND()'; // database specific random keyword
 
 	/**
@@ -61,13 +58,21 @@ class CI_DB_mysqli_driver extends CI_DB {
 	/**
 	 * Non-persistent database connection
 	 *
+	 * @param	bool
 	 * @return	object
+	 * @todo	SSL support
 	 */
-	public function db_connect()
+	public function db_connect($persistent = FALSE)
 	{
-		return empty($this->port)
-			? @new mysqli($this->hostname, $this->username, $this->password, $this->database)
-			: @new mysqli($this->hostname, $this->username, $this->password, $this->database, $this->port);
+		// Persistent connection support was added in PHP 5.3.0
+		$hostname = ($persistent === TRUE && is_php('5.3'))
+			? 'p:'.$this->hostname : $this->hostname;
+		$port = empty($this->port) ? NULL : $this->port;
+		$client_flags = ($this->compress === TRUE) ? MYSQLI_CLIENT_COMPRESS : 0;
+		$mysqli = mysqli_init();
+
+		return @$mysqli->real_connect($hostname, $this->username, $this->password, $this->database, $port, NULL, $client_flags)
+			? $mysqli : FALSE;
 	}
 
 	// --------------------------------------------------------------------
@@ -79,15 +84,7 @@ class CI_DB_mysqli_driver extends CI_DB {
 	 */
 	public function db_pconnect()
 	{
-		// Persistent connection support was added in PHP 5.3.0
-		if ( ! is_php('5.3'))
-		{
-			return $this->db_connect();
-		}
-
-		return empty($this->port)
-			? @new mysqli('p:'.$this->hostname, $this->username, $this->password, $this->database)
-			: @new mysqli('p:'.$this->hostname, $this->username, $this->password, $this->database, $this->port);
+		return $this->db_connect(TRUE);
 	}
 
 	// --------------------------------------------------------------------
@@ -199,6 +196,7 @@ class CI_DB_mysqli_driver extends CI_DB {
 	/**
 	 * Begin Transaction
 	 *
+	 * @param	bool	$test_mode = FALSE
 	 * @return	bool
 	 */
 	public function trans_begin($test_mode = FALSE)
@@ -400,6 +398,14 @@ class CI_DB_mysqli_driver extends CI_DB {
 	 */
 	public function error()
 	{
+		if ( ! empty($this->conn_id->connect_errno))
+		{
+			return array(
+				'code' => $this->conn_id->connect_errno,
+				'message' => is_php('5.2.9') ? $this->conn_id->connect_error : mysqli_connect_error()
+			);
+		}
+
 		return array('code' => $this->conn_id->errno, 'message' => $this->conn_id->error);
 	}
 
@@ -412,10 +418,10 @@ class CI_DB_mysqli_driver extends CI_DB {
 	 *
 	 * @param	string	the table name
 	 * @param	array	the update data
-	 * @param	array	the where clause
+	 * @param	string	the where key
 	 * @return	string
 	 */
-	protected function _update_batch($table, $values, $index, $where = NULL)
+	protected function _update_batch($table, $values, $index)
 	{
 		$ids = array();
 		foreach ($values as $key => $val)
@@ -439,11 +445,29 @@ class CI_DB_mysqli_driver extends CI_DB {
 				.'ELSE '.$k.' END, ';
 		}
 
-		$where = ($where !== '' && count($where) > 0) ? implode(' ', $where).' AND ' : '';
+		$this->where($index.' IN('.implode(',', $ids).')', NULL, FALSE);
+
+		return 'UPDATE '.$table.' SET '.substr($cases, 0, -2).$this->_compile_wh('qb_where');
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * FROM tables
+	 *
+	 * Groups tables in FROM clauses if needed, so there is no confusion
+	 * about operator precedence.
+	 *
+	 * @return	string
+	 */
+	protected function _from_tables()
+	{
+		if ( ! empty($this->qb_join) && count($this->qb_from) > 1)
+		{
+			return '('.implode(', ', $this->qb_from).')';
+		}
 
-		return 'UPDATE '.$table.' SET '.substr($cases, 0, -2)
-			.' WHERE '.(($where !== '' && count($where) > 0) ? implode(' ', $where).' AND ' : '')
-			.$index.' IN('.implode(',', $ids).')';
+		return implode(', ', $this->qb_from);
 	}
 
 	// --------------------------------------------------------------------
diff --git a/system/database/drivers/mysqli/mysqli_result.php b/system/database/drivers/mysqli/mysqli_result.php
index c1ec4da76..f036302bb 100644
--- a/system/database/drivers/mysqli/mysqli_result.php
+++ b/system/database/drivers/mysqli/mysqli_result.php
@@ -132,6 +132,7 @@ class CI_DB_mysqli_result extends CI_DB_result {
 	 * this internally before fetching results to make sure the
 	 * result set starts at zero
 	 *
+	 * @param	int	$n = 0
 	 * @return	bool
 	 */
 	protected function _data_seek($n = 0)
diff --git a/system/database/drivers/oci8/oci8_driver.php b/system/database/drivers/oci8/oci8_driver.php
index 691247fee..81d73d073 100644
--- a/system/database/drivers/oci8/oci8_driver.php
+++ b/system/database/drivers/oci8/oci8_driver.php
@@ -54,10 +54,6 @@ class CI_DB_oci8_driver extends CI_DB {
 	// The character used for excaping
 	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
@@ -79,6 +75,12 @@ class CI_DB_oci8_driver extends CI_DB {
 	// throw off num_fields later
 	public $limit_used;
 
+	/**
+	 * Constructor
+	 *
+	 * @param	array	$params
+	 * @return	void
+	 */
 	public function __construct($params)
 	{
 		parent::__construct($params);
@@ -547,22 +549,6 @@ class CI_DB_oci8_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($tables)
-	{
-		return is_array($tables) ? implode(', ', $tables) : $tables;
-	}
-
-	// --------------------------------------------------------------------
-
-	/**
 	 * Insert_batch statement
 	 *
 	 * Generates a platform-specific insert string from the supplied data
@@ -611,20 +597,17 @@ class CI_DB_oci8_driver extends CI_DB {
 	 * Generates a platform-specific delete string from the supplied data
 	 *
 	 * @param	string	the table name
-	 * @param	array	the where clause
-	 * @param	array	the like clause
-	 * @param	string	the limit clause
 	 * @return	string
 	 */
-	protected function _delete($table, $where = array(), $like = array(), $limit = FALSE)
+	protected function _delete($table)
 	{
-		$conditions = array();
-
-		empty($where) OR $conditions[] = implode(' ', $where);
-		empty($like) OR $conditions[] = implode(' ', $like);
-		empty($limit) OR $conditions[] = 'rownum <= '.$limit;
+		if ($this->qb_limit)
+		{
+			$this->where('rownum <= ',$this->qb_limit, FALSE);
+			$this->qb_limit = FALSE;
+		}
 
-		return 'DELETE FROM '.$table.(count($conditions) > 0 ? ' WHERE '.implode(' AND ', $conditions) : '');
+		return parent::_delete($table);
 	}
 
 	// --------------------------------------------------------------------
@@ -635,15 +618,13 @@ class CI_DB_oci8_driver extends CI_DB {
 	 * 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, $offset)
+	protected function _limit($sql)
 	{
 		$this->limit_used = TRUE;
-		return 'SELECT * FROM (SELECT inner_query.*, rownum rnum FROM ('.$sql.') inner_query WHERE rownum < '.($offset + $limit + 1).')'
-			.($offset ? ' WHERE rnum >= '.($offset + 1): '');
+		return 'SELECT * FROM (SELECT inner_query.*, rownum rnum FROM ('.$sql.') inner_query WHERE rownum < '.($this->qb_offset + $this->qb_limit + 1).')'
+			.($this->qb_offset ? ' WHERE rnum >= '.($this->qb_offset + 1): '');
 	}
 
 	// --------------------------------------------------------------------
diff --git a/system/database/drivers/odbc/odbc_driver.php b/system/database/drivers/odbc/odbc_driver.php
index 8f0a474b0..063a04b98 100644
--- a/system/database/drivers/odbc/odbc_driver.php
+++ b/system/database/drivers/odbc/odbc_driver.php
@@ -45,12 +45,16 @@ class CI_DB_odbc_driver extends CI_DB {
 	// the character used to excape - not necessary for ODBC
 	protected $_escape_char = '';
 
-	// clause and character used for LIKE escape sequences
 	protected $_like_escape_str = " {escape '%s'} ";
-	protected $_like_escape_chr = '!';
 
 	protected $_random_keyword;
 
+	/**
+	 * Constructor
+	 *
+	 * @param	array	$params
+	 * @return	void
+	 */
 	public function __construct($params)
 	{
 		parent::__construct($params);
@@ -64,6 +68,8 @@ class CI_DB_odbc_driver extends CI_DB {
 		}
 	}
 
+	// --------------------------------------------------------------------
+
 	/**
 	 * Non-persistent database connection
 	 *
@@ -104,6 +110,7 @@ class CI_DB_odbc_driver extends CI_DB {
 	/**
 	 * Begin Transaction
 	 *
+	 * @param	bool	$test_mode = FALSE
 	 * @return	bool
 	 */
 	public function trans_begin($test_mode = FALSE)
@@ -291,17 +298,19 @@ class CI_DB_odbc_driver extends CI_DB {
 	// --------------------------------------------------------------------
 
 	/**
-	 * From Tables
+	 * Update statement
 	 *
-	 * This function implicitly groups FROM tables so there is no confusion
-	 * about operator precedence in harmony with SQL standards
+	 * Generates a platform-specific update string from the supplied data
 	 *
-	 * @param	array
+	 * @param	string	the table name
+	 * @param	array	the update data
 	 * @return	string
-	 */
-	protected function _from_tables($tables)
+         */
+	protected function _update($table, $values)
 	{
-		return is_array($tables) ? implode(', ', $tables) : $tables;
+		$this->qb_limit = FALSE;
+		$this->qb_orderby = array();
+		return parent::_update($table, $values);
 	}
 
 	// --------------------------------------------------------------------
@@ -325,6 +334,22 @@ class CI_DB_odbc_driver extends CI_DB {
 	// --------------------------------------------------------------------
 
 	/**
+	 * Delete statement
+	 *
+	 * Generates a platform-specific delete string from the supplied data
+	 *
+	 * @param	string	the table name
+	 * @return	string
+	 */
+	protected function _delete($table)
+	{
+		$this->qb_limit = FALSE;
+		return parent::_delete($table);
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
 	 * Close DB Connection
 	 *
 	 * @return	void
diff --git a/system/database/drivers/pdo/pdo_driver.php b/system/database/drivers/pdo/pdo_driver.php
index 705b16560..32a9e7509 100644
--- a/system/database/drivers/pdo/pdo_driver.php
+++ b/system/database/drivers/pdo/pdo_driver.php
@@ -45,10 +45,6 @@ class CI_DB_pdo_driver extends CI_DB {
 	// 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 = '!';
-
 	protected $_random_keyword;
 
 	public $trans_enabled = FALSE;
@@ -61,7 +57,7 @@ class CI_DB_pdo_driver extends CI_DB {
 	 *
 	 * Validates the DSN string and/or detects the subdriver
 	 *
-	 * @param	array
+	 * @param	array	$params
 	 * @return	void
 	 */
 	public function __construct($params)
@@ -187,6 +183,7 @@ class CI_DB_pdo_driver extends CI_DB {
 	/**
 	 * Begin Transaction
 	 *
+	 * @param	bool	$test_mode = FALSE
 	 * @return	bool
 	 */
 	public function trans_begin($test_mode = FALSE)
@@ -360,14 +357,12 @@ class CI_DB_pdo_driver extends CI_DB {
 	 *
 	 * @param	string	the table name
 	 * @param	array	the update data
-	 * @param	array	the where clause
+	 * @param	string	the where key
 	 * @return	string
 	 */
-	protected function _update_batch($table, $values, $index, $where = NULL)
+	protected function _update_batch($table, $values, $index)
 	{
 		$ids = array();
-		$where = ($where !== '' && count($where) >=1) ? implode(' ', $where).' AND ' : '';
-
 		foreach ($values as $key => $val)
 		{
 			$ids[] = $val[$index];
@@ -381,9 +376,7 @@ class CI_DB_pdo_driver extends CI_DB {
 			}
 		}
 
-		$sql   = 'UPDATE '.$table.' SET ';
 		$cases = '';
-
 		foreach ($final as $k => $v)
 		{
 			$cases .= $k.' = CASE '."\n";
@@ -396,10 +389,9 @@ class CI_DB_pdo_driver extends CI_DB {
 			$cases .= 'ELSE '.$k.' END, ';
 		}
 
-		$sql .= substr($cases, 0, -2);
-		$sql .= ' WHERE '.$where.$index.' IN ('.implode(',', $ids).')';
+		$this->where($index.' IN('.implode(',', $ids).')', NULL, FALSE);
 
-		return $sql;
+		return 'UPDATE '.$table.' SET '.substr($cases, 0, -2).$this->_compile_wh('qb_where');
 	}
 
 	// --------------------------------------------------------------------
diff --git a/system/database/drivers/pdo/subdrivers/pdo_4d_driver.php b/system/database/drivers/pdo/subdrivers/pdo_4d_driver.php
index e287f5c63..438d312a1 100644
--- a/system/database/drivers/pdo/subdrivers/pdo_4d_driver.php
+++ b/system/database/drivers/pdo/subdrivers/pdo_4d_driver.php
@@ -130,49 +130,19 @@ class CI_DB_pdo_4d_driver extends CI_DB_pdo_driver {
 	// --------------------------------------------------------------------
 
 	/**
-	 * 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, $like = array())
+	protected function _update($table, $values)
 	{
-		foreach ($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;
+		$this->qb_limit = FALSE;
+		$this->qb_orderby = array();
+		return parent::_update($table, $values);
 	}
 
 	// --------------------------------------------------------------------
@@ -183,21 +153,12 @@ class CI_DB_pdo_4d_driver extends CI_DB_pdo_driver {
 	 * 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(), $limit = FALSE)
+	protected function _delete($table)
 	{
-		$conditions = array();
-
-		empty($where) OR $conditions[] = implode(' ', $where);
-		empty($like) OR $conditions[] = implode(' ', $like);
-
-		$conditions = (count($conditions) > 0) ? ' WHERE '.implode(' AND ', $conditions) : '';
-
-		return 'DELETE FROM '.$table.$conditions;
+		$this->qb_limit = FALSE;
+		return parent::_delete($table);
 	}
 
 	// --------------------------------------------------------------------
@@ -208,13 +169,11 @@ class CI_DB_pdo_4d_driver extends CI_DB_pdo_driver {
 	 * 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, $offset)
+	protected function _limit($sql)
 	{
-		return $sql.' LIMIT '.$limit.($offset ? ' OFFSET '.$offset : '');
+		return $sql.' LIMIT '.$this->qb_limit.($this->qb_offset ? ' OFFSET '.$this->qb_offset : '');
 	}
 
 }
diff --git a/system/database/drivers/pdo/subdrivers/pdo_cubrid_driver.php b/system/database/drivers/pdo/subdrivers/pdo_cubrid_driver.php
index 05eeacfe6..d2a484d9e 100644
--- a/system/database/drivers/pdo/subdrivers/pdo_cubrid_driver.php
+++ b/system/database/drivers/pdo/subdrivers/pdo_cubrid_driver.php
@@ -44,10 +44,6 @@ class CI_DB_pdo_cubrid_driver extends CI_DB_pdo_driver {
 
 	protected $_escape_char = '`';
 
-	// clause and character used for LIKE escape sequences - not used in CUBRID
-	protected $_like_escape_str = '';
-	protected $_like_escape_chr = '\\';
-
 	protected $_random_keyword = ' RAND()';
 
 	/**
@@ -133,10 +129,10 @@ class CI_DB_pdo_cubrid_driver extends CI_DB_pdo_driver {
 	 *
 	 * @param	string	the table name
 	 * @param	array	the update data
-	 * @param	array	the where clause
+	 * @param	string	the where key
 	 * @return	string
 	 */
-	protected function _update_batch($table, $values, $index, $where = NULL)
+	protected function _update_batch($table, $values, $index)
 	{
 		$ids = array();
 		foreach ($values as $key => $val)
@@ -160,9 +156,9 @@ class CI_DB_pdo_cubrid_driver extends CI_DB_pdo_driver {
 				.'ELSE '.$k.' END), ';
 		}
 
-		return 'UPDATE '.$table.' SET '.substr($cases, 0, -2)
-			.' WHERE '.(($where !== '' && count($where) > 0) ? implode(' ', $where).' AND ' : '')
-			.$index.' IN('.implode(',', $ids).')';
+		$this->where($index.' IN('.implode(',', $ids).')', NULL, FALSE);
+
+		return 'UPDATE '.$table.' SET '.substr($cases, 0, -2).$this->_compile_wh('qb_where');
 	}
 
 	// --------------------------------------------------------------------
@@ -183,6 +179,26 @@ class CI_DB_pdo_cubrid_driver extends CI_DB_pdo_driver {
 		return 'TRUNCATE '.$table;
 	}
 
+	// --------------------------------------------------------------------
+
+	/**
+	 * FROM tables
+	 *
+	 * Groups tables in FROM clauses if needed, so there is no confusion
+	 * about operator precedence.
+	 *
+	 * @return	string
+	 */
+	protected function _from_tables()
+	{
+		if ( ! empty($this->qb_join) && count($this->qb_from) > 1)
+		{
+			return '('.implode(', ', $this->qb_from).')';
+		}
+
+		return implode(', ', $this->qb_from);
+	}
+
 }
 
 /* End of file pdo_cubrid_driver.php */
diff --git a/system/database/drivers/pdo/subdrivers/pdo_dblib_driver.php b/system/database/drivers/pdo/subdrivers/pdo_dblib_driver.php
index 7060c9eb9..785b2795c 100644
--- a/system/database/drivers/pdo/subdrivers/pdo_dblib_driver.php
+++ b/system/database/drivers/pdo/subdrivers/pdo_dblib_driver.php
@@ -153,49 +153,19 @@ class CI_DB_pdo_dblib_driver extends CI_DB_pdo_driver {
 	// --------------------------------------------------------------------
 
 	/**
-	 * 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, $like = array())
+	protected function _update($table, $values)
 	{
-		foreach ($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;
+		$this->qb_limit = FALSE;
+		$this->qb_orderby = array();
+		return parent::_update($table, $values);
 	}
 
 	// --------------------------------------------------------------------
@@ -206,23 +176,16 @@ class CI_DB_pdo_dblib_driver extends CI_DB_pdo_driver {
 	 * 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(), $limit = FALSE)
+	protected function _delete($table)
 	{
-		$conditions = array();
-
-		empty($where) OR $conditions[] = implode(' ', $where);
-		empty($like) OR $conditions[] = implode(' ', $like);
-
-		$conditions = (count($conditions) > 0) ? ' WHERE '.implode(' AND ', $conditions) : '';
+		if ($this->qb_limit)
+		{
+			return 'WITH ci_delete AS (SELECT TOP '.$this->qb_limit.' * FROM '.$table.$this->_compile_wh('qb_where').') DELETE FROM ci_delete';
+		}
 
-		return ($limit)
-			? 'WITH ci_delete AS (SELECT TOP '.$limit.' * FROM '.$table.$conditions.') DELETE FROM ci_delete'
-			: 'DELETE FROM '.$table.$conditions;
+		return parent::_delete($table);
 	}
 
 	// --------------------------------------------------------------------
@@ -233,27 +196,44 @@ class CI_DB_pdo_dblib_driver extends CI_DB_pdo_driver {
 	 * 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, $offset)
+	protected function _limit($sql)
 	{
-		$limit = $offset + $limit;
+		$limit = $this->qb_offset + $this->qb_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))
+		if (version_compare($this->version(), '9', '>=') && $this->qb_offset && ! empty($this->qb_orderby))
 		{
-			$orderby = 'ORDER BY '.implode(', ', $this->qb_orderby);
+			$orderby = $this->_compile_order_by();
 
 			// We have to strip the ORDER BY clause
-			$sql = trim(substr($sql, 0, strrpos($sql, 'ORDER BY '.$orderby)));
+			$sql = trim(substr($sql, 0, strrpos($sql, $orderby)));
+
+			// Get the fields to select from our subquery, so that we can avoid CI_rownum appearing in the actual results
+			if (count($this->qb_select) === 0)
+			{
+				$select = '*'; // Inevitable
+			}
+			else
+			{
+				// Use only field names and their aliases, everything else is out of our scope.
+				$select = array();
+				$field_regexp = ($this->_quoted_identifier)
+					? '("[^\"]+")' : '(\[[^\]]+\])';
+				for ($i = 0, $c = count($this->qb_select); $i < $c; $i++)
+				{
+					$select[] = preg_match('/(?:\s|\.)'.$field_regexp.'$/i', $this->qb_select[$i], $m)
+						? $m[1] : $this->qb_select[$i];
+				}
+				$select = implode(', ', $select);
+			}
 
-			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 'SELECT '.$select." FROM (\n\n"
+				.preg_replace('/^(SELECT( DISTINCT)?)/i', '\\1 ROW_NUMBER() OVER('.trim($orderby).') AS '.$this->escape_identifiers('CI_rownum').', ', $sql)
+				."\n\n) ".$this->escape_identifiers('CI_subquery')
+				."\nWHERE ".$this->escape_identifiers('CI_rownum').' BETWEEN '.($this->qb_offset + 1).' AND '.$limit;
 		}
 
 		return preg_replace('/(^\SELECT (DISTINCT)?)/i','\\1 TOP '.$limit.' ', $sql);
@@ -262,4 +242,4 @@ class CI_DB_pdo_dblib_driver extends CI_DB_pdo_driver {
 }
 
 /* End of file pdo_dblib_driver.php */
-/* Location: ./system/database/drivers/pdo/subdrivers/pdo_dblib_driver.php */
+/* Location: ./system/database/drivers/pdo/subdrivers/pdo_dblib_driver.php */
\ No newline at end of file
diff --git a/system/database/drivers/pdo/subdrivers/pdo_firebird_driver.php b/system/database/drivers/pdo/subdrivers/pdo_firebird_driver.php
index c074a9a78..32d1f219a 100644
--- a/system/database/drivers/pdo/subdrivers/pdo_firebird_driver.php
+++ b/system/database/drivers/pdo/subdrivers/pdo_firebird_driver.php
@@ -139,51 +139,18 @@ class CI_DB_pdo_firebird_driver extends CI_DB_pdo_driver {
 	// --------------------------------------------------------------------
 
 	/**
-	 * 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, $like = array())
+	protected function _update($table, $values)
 	{
-		foreach ($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) : '');
+		$this->qb_limit = FALSE;
+		return parent::_update($table, $values);
 	}
 
 	// --------------------------------------------------------------------
@@ -212,19 +179,12 @@ class CI_DB_pdo_firebird_driver extends CI_DB_pdo_driver {
 	 * 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(), $limit = FALSE)
+	protected function _delete($table)
 	{
-		$conditions = array();
-
-		empty($where) OR $conditions[] = implode(' ', $where);
-		empty($like) OR $conditions[] = implode(' ', $like);
-
-		return 'DELETE FROM '.$table.(count($conditions) > 0 ? ' WHERE '.implode(' AND ', $conditions) : '');
+		$this->qb_limit = FALSE;
+		return parent::_delete($table);
 	}
 
 	// --------------------------------------------------------------------
@@ -235,22 +195,20 @@ class CI_DB_pdo_firebird_driver extends CI_DB_pdo_driver {
 	 * 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, $offset)
+	protected function _limit($sql)
 	{
 		// Limit clause depends on if Interbase or Firebird
 		if (stripos($this->version(), 'firebird') !== FALSE)
 		{
-			$select = 'FIRST '. (int) $limit
-				.($offset > 0 ? ' SKIP '. (int) $offset : '');
+			$select = 'FIRST '.$this->qb_limit
+				.($this->qb_offset > 0 ? ' SKIP '.$this->qb_offset : '');
 		}
 		else
 		{
 			$select = 'ROWS '
-				.($offset > 0 ? (int) $offset.' TO '.($limit + $offset) : (int) $limit);
+				.($this->qb_offset > 0 ? $this->qb_offset.' TO '.($this->qb_limit + $this->qb_offset) : $this->qb_limit);
 		}
 
 		return preg_replace('`SELECT`i', 'SELECT '.$select, $sql);
diff --git a/system/database/drivers/pdo/subdrivers/pdo_ibm_driver.php b/system/database/drivers/pdo/subdrivers/pdo_ibm_driver.php
index 832c03c96..22a5f928c 100644
--- a/system/database/drivers/pdo/subdrivers/pdo_ibm_driver.php
+++ b/system/database/drivers/pdo/subdrivers/pdo_ibm_driver.php
@@ -165,49 +165,19 @@ class CI_DB_pdo_ibm_driver extends CI_DB_pdo_driver {
 	// --------------------------------------------------------------------
 
 	/**
-	 * 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, $like = array())
+	protected function _update($table, $values)
 	{
-		foreach ($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;
+		$this->qb_limit = FALSE;
+		$this->qb_orderby = array();
+		return parent::_update($table, $values);
 	}
 
 	// --------------------------------------------------------------------
@@ -218,21 +188,12 @@ class CI_DB_pdo_ibm_driver extends CI_DB_pdo_driver {
 	 * 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(), $limit = FALSE)
+	protected function _delete($table)
 	{
-		$conditions = array();
-
-		empty($where) OR $conditions[] = implode(' ', $where);
-		empty($like) OR $conditions[] = implode(' ', $like);
-
-		$conditions = (count($conditions) > 0) ? ' WHERE '.implode(' AND ', $conditions) : '';
-
-		return 'DELETE FROM '.$table.$conditions;
+		$this->qb_limit = FALSE;
+		return parent::_delete($table);
 	}
 
 	// --------------------------------------------------------------------
diff --git a/system/database/drivers/pdo/subdrivers/pdo_informix_driver.php b/system/database/drivers/pdo/subdrivers/pdo_informix_driver.php
index a3efc63dc..8dd430184 100644
--- a/system/database/drivers/pdo/subdrivers/pdo_informix_driver.php
+++ b/system/database/drivers/pdo/subdrivers/pdo_informix_driver.php
@@ -159,49 +159,19 @@ class CI_DB_pdo_informix_driver extends CI_DB_pdo_driver {
 	// --------------------------------------------------------------------
 
 	/**
-	 * 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, $like = array())
+	protected function _update($table, $values)
 	{
-		foreach ($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;
+		$this->qb_limit = FALSE;
+		$this->qb_orderby = array();
+		return parent::_update($table, $values);
 	}
 
 	// --------------------------------------------------------------------
@@ -230,21 +200,12 @@ class CI_DB_pdo_informix_driver extends CI_DB_pdo_driver {
 	 * 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(), $limit = FALSE)
+	protected function _delete($table)
 	{
-		$conditions = array();
-
-		empty($where) OR $conditions[] = implode(' ', $where);
-		empty($like) OR $conditions[] = implode(' ', $like);
-
-		$conditions = (count($conditions) > 0) ? ' WHERE '.implode(' AND ', $conditions) : '';
-
-		return 'DELETE FROM '.$table.$conditions;
+		$this->qb_limit = FALSE;
+		return parent::_delete($table);
 	}
 
 	// --------------------------------------------------------------------
@@ -255,13 +216,11 @@ class CI_DB_pdo_informix_driver extends CI_DB_pdo_driver {
 	 * 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, $offset)
+	protected function _limit($sql)
 	{
-		$select = 'SELECT '.($offset ? 'SKIP '.$offset : '').'FIRST '.$limit.' ';
+		$select = 'SELECT '.($this->qb_offset ? 'SKIP '.$this->qb_offset : '').'FIRST '.$this->qb_limit.' ';
 		return preg_replace('/^(SELECT\s)/i', $select, $sql, 1);
 	}
 
diff --git a/system/database/drivers/pdo/subdrivers/pdo_mysql_driver.php b/system/database/drivers/pdo/subdrivers/pdo_mysql_driver.php
index 78afe246c..0fb5d8f12 100644
--- a/system/database/drivers/pdo/subdrivers/pdo_mysql_driver.php
+++ b/system/database/drivers/pdo/subdrivers/pdo_mysql_driver.php
@@ -41,13 +41,10 @@
 class CI_DB_pdo_mysql_driver extends CI_DB_pdo_driver {
 
 	public $subdriver = 'mysql';
+	public $compress = FALSE;
 
 	protected $_escape_char = '`';
 
-	// clause and character used for LIKE escape sequences - not used in MySQL
-	protected $_like_escape_str = '';
-	protected $_like_escape_chr = '\\';
-
 	protected $_random_keyword = ' RAND()';
 
 	/**
@@ -83,6 +80,7 @@ class CI_DB_pdo_mysql_driver extends CI_DB_pdo_driver {
 	 *
 	 * @param	bool
 	 * @return	object
+	 * @todo	SSL support
 	 */
 	public function db_connect($persistent = FALSE)
 	{
@@ -97,6 +95,11 @@ class CI_DB_pdo_mysql_driver extends CI_DB_pdo_driver {
 				.(empty($this->dbcollat) ? '' : ' COLLATE '.$this->dbcollat);
 		}
 
+		if ($this->compress === TRUE)
+		{
+			$this->options[PDO::MYSQL_ATTR_COMPRESS] = TRUE;
+		}
+
 		return parent::db_connect($persistent);
 	}
 
@@ -161,10 +164,10 @@ class CI_DB_pdo_mysql_driver extends CI_DB_pdo_driver {
 	 *
 	 * @param	string	the table name
 	 * @param	array	the update data
-	 * @param	array	the where clause
+	 * @param	string	the where key
 	 * @return	string
 	 */
-	protected function _update_batch($table, $values, $index, $where = NULL)
+	protected function _update_batch($table, $values, $index)
 	{
 		$ids = array();
 		foreach ($values as $key => $val)
@@ -188,9 +191,9 @@ class CI_DB_pdo_mysql_driver extends CI_DB_pdo_driver {
 				.'ELSE '.$k.' END), ';
 		}
 
-		return 'UPDATE '.$table.' SET '.substr($cases, 0, -2)
-			.' WHERE '.(($where !== '' && count($where) > 0) ? implode(' ', $where).' AND ' : '')
-			.$index.' IN('.implode(',', $ids).')';
+		$this->where($index.' IN('.implode(',', $ids).')', NULL, FALSE);
+
+		return 'UPDATE '.$table.' SET '.substr($cases, 0, -2).$this->_compile_wh('qb_where');
 	}
 
 	// --------------------------------------------------------------------
@@ -211,6 +214,26 @@ class CI_DB_pdo_mysql_driver extends CI_DB_pdo_driver {
 		return 'TRUNCATE '.$table;
 	}
 
+	// --------------------------------------------------------------------
+
+	/**
+	 * FROM tables
+	 *
+	 * Groups tables in FROM clauses if needed, so there is no confusion
+	 * about operator precedence.
+	 *
+	 * @return	string
+	 */
+	protected function _from_tables()
+	{
+		if ( ! empty($this->qb_join) && count($this->qb_from) > 1)
+		{
+			return '('.implode(', ', $this->qb_from).')';
+		}
+
+		return implode(', ', $this->qb_from);
+	}
+
 }
 
 /* End of file pdo_mysql_driver.php */
diff --git a/system/database/drivers/pdo/subdrivers/pdo_oci_driver.php b/system/database/drivers/pdo/subdrivers/pdo_oci_driver.php
index 56ec1bce1..b03218fad 100644
--- a/system/database/drivers/pdo/subdrivers/pdo_oci_driver.php
+++ b/system/database/drivers/pdo/subdrivers/pdo_oci_driver.php
@@ -146,22 +146,6 @@ class CI_DB_pdo_oci_driver extends CI_DB_pdo_driver {
 	// --------------------------------------------------------------------
 
 	/**
-	 * 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) : $tables;
-	}
-
-	// --------------------------------------------------------------------
-
-	/**
 	 * Insert_batch statement
 	 *
 	 * @param	string	the table name
@@ -190,20 +174,17 @@ class CI_DB_pdo_oci_driver extends CI_DB_pdo_driver {
 	 * Generates a platform-specific delete string from the supplied data
 	 *
 	 * @param	string	the table name
-	 * @param	array	the where clause
-	 * @param	array	the like clause
-	 * @param	string	the limit clause
 	 * @return	string
 	 */
-	protected function _delete($table, $where = array(), $like = array(), $limit = FALSE)
+	protected function _delete($table)
 	{
-		$conditions = array();
-
-		empty($where) OR $conditions[] = implode(' ', $where);
-		empty($like) OR $conditions[] = implode(' ', $like);
-		empty($limit) OR $conditions[] = 'rownum <= '.$limit;
+		if ($this->qb_limit)
+		{
+			$this->where('rownum <= ',$this->qb_limit, FALSE);
+			$this->qb_limit = FALSE;
+		}
 
-		return 'DELETE FROM '.$table.(count($conditions) > 0 ? ' WHERE '.implode(' AND ', $conditions) : '');
+		return parent::_delete($table);
 	}
 
 	// --------------------------------------------------------------------
@@ -214,14 +195,12 @@ class CI_DB_pdo_oci_driver extends CI_DB_pdo_driver {
 	 * 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, $offset)
+	protected function _limit($sql)
 	{
-		return 'SELECT * FROM (SELECT inner_query.*, rownum rnum FROM ('.$sql.') inner_query WHERE rownum < '.($offset + $limit + 1).')'
-			.($offset ? ' WHERE rnum >= '.($offset + 1): '');
+		return 'SELECT * FROM (SELECT inner_query.*, rownum rnum FROM ('.$sql.') inner_query WHERE rownum < '.($this->qb_offset + $this->qb_limit + 1).')'
+			.($this->qb_offset ? ' WHERE rnum >= '.($this->qb_offset + 1): '');
 	}
 
 }
diff --git a/system/database/drivers/pdo/subdrivers/pdo_odbc_driver.php b/system/database/drivers/pdo/subdrivers/pdo_odbc_driver.php
index 392754ff7..5944d55f4 100644
--- a/system/database/drivers/pdo/subdrivers/pdo_odbc_driver.php
+++ b/system/database/drivers/pdo/subdrivers/pdo_odbc_driver.php
@@ -46,7 +46,6 @@ class CI_DB_pdo_odbc_driver extends CI_DB_pdo_driver {
 	protected $_escape_char = '';
 
 	// clause and character used for LIKE escape sequences
-	protected $_like_escape_chr = '!';
 	protected $_like_escape_str = " {escape '%s'} ";
 
 	protected $_random_keyword = ' RAND()';
@@ -157,49 +156,19 @@ class CI_DB_pdo_odbc_driver extends CI_DB_pdo_driver {
 	// --------------------------------------------------------------------
 
 	/**
-	 * 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, $like = array())
+	protected function _update($table, $values)
 	{
-		foreach ($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;
+		$this->qb_limit = FALSE;
+		$this->qb_orderby = array();
+		return parent::_update($table, $values);
 	}
 
 	// --------------------------------------------------------------------
@@ -228,21 +197,12 @@ class CI_DB_pdo_odbc_driver extends CI_DB_pdo_driver {
 	 * 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(), $limit = FALSE)
+	protected function _delete($table)
 	{
-		$conditions = array();
-
-		empty($where) OR $conditions[] = implode(' ', $where);
-		empty($like) OR $conditions[] = implode(' ', $like);
-
-		$conditions = (count($conditions) > 0) ? ' WHERE '.implode(' AND ', $conditions) : '';
-
-		return 'DELETE FROM '.$table.$conditions;
+		$this->qb_limit = FALSE;
+		return parent::_delete($table);
 	}
 
 	// --------------------------------------------------------------------
@@ -253,13 +213,11 @@ class CI_DB_pdo_odbc_driver extends CI_DB_pdo_driver {
 	 * 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, $offset)
+	protected function _limit($sql)
 	{
-		return preg_replace('/(^\SELECT (DISTINCT)?)/i','\\1 TOP '.$limit.' ', $sql);
+		return preg_replace('/(^\SELECT (DISTINCT)?)/i','\\1 TOP '.$this->qb_limit.' ', $sql);
 	}
 
 }
diff --git a/system/database/drivers/pdo/subdrivers/pdo_pgsql_driver.php b/system/database/drivers/pdo/subdrivers/pdo_pgsql_driver.php
index 9a476f143..74d56e6b8 100644
--- a/system/database/drivers/pdo/subdrivers/pdo_pgsql_driver.php
+++ b/system/database/drivers/pdo/subdrivers/pdo_pgsql_driver.php
@@ -142,49 +142,19 @@ class CI_DB_pdo_pgsql_driver extends CI_DB_pdo_driver {
 	// --------------------------------------------------------------------
 
 	/**
-	 * 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, $like = array())
+	protected function _update($table, $values)
 	{
-		foreach ($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;
+		$this->qb_limit = FALSE;
+		$this->qb_orderby = array();
+		return parent::_update($table, $values);
 	}
 
 	// --------------------------------------------------------------------
@@ -196,10 +166,10 @@ class CI_DB_pdo_pgsql_driver extends CI_DB_pdo_driver {
 	 *
 	 * @param	string	the table name
 	 * @param	array	the update data
-	 * @param	array	the where clause
+	 * @param	string	the where key
 	 * @return	string
 	 */
-	protected function _update_batch($table, $values, $index, $where = NULL)
+	protected function _update_batch($table, $values, $index)
 	{
 		$ids = array();
 		foreach ($values as $key => $val)
@@ -218,14 +188,14 @@ class CI_DB_pdo_pgsql_driver extends CI_DB_pdo_driver {
 		$cases = '';
 		foreach ($final as $k => $v)
 		{
-			$cases .= $k.' = (CASE '.$k."\n"
+			$cases .= $k.' = (CASE '.$index."\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).')';
+		$this->where($index.' IN('.implode(',', $ids).')', NULL, FALSE);
+
+		return 'UPDATE '.$table.' SET '.substr($cases, 0, -2).$this->_compile_wh('qb_where');
 	}
 
 	// --------------------------------------------------------------------
@@ -236,19 +206,12 @@ class CI_DB_pdo_pgsql_driver extends CI_DB_pdo_driver {
 	 * 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(), $limit = FALSE)
+	protected function _delete($table)
 	{
-		$conditions = array();
-
-		empty($where) OR $conditions[] = implode(' ', $where);
-		empty($like) OR $conditions[] = implode(' ', $like);
-
-		return 'DELETE FROM '.$table.(count($conditions) > 0 ? ' WHERE '.implode(' AND ', $conditions) : '');
+		$this->qb_limit = FALSE;
+		return parent::_delete($table);
 	}
 
 	// --------------------------------------------------------------------
@@ -259,29 +222,31 @@ class CI_DB_pdo_pgsql_driver extends CI_DB_pdo_driver {
 	 * 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, $offset)
+	protected function _limit($sql)
 	{
-		return $sql.' LIMIT '.$limit.($offset ? ' OFFSET '.$offset : '');
+		return $sql.' LIMIT '.$this->qb_limit.($this->qb_offset ? ' OFFSET '.$this->qb_offset : '');
 	}
 
 	// --------------------------------------------------------------------
 
 	/**
-	 * Where
+	 * WHERE, HAVING
 	 *
-	 * Called by where() or or_where()
+	 * Called by where(), or_where(), having(), or_having()
 	 *
+	 * @param	string	'qb_where' or 'qb_having'
 	 * @param	mixed
 	 * @param	mixed
 	 * @param	string
+	 * @param	bool
 	 * @return	object
 	 */
-	protected function _where($key, $value = NULL, $type = 'AND ', $escape = NULL)
+	protected function _wh($qb_key, $key, $value = NULL, $type = 'AND ', $escape = NULL)
 	{
+		$qb_cache_key = ($qb_key === 'qb_having') ? 'qb_cache_having' : 'qb_cache_where';
+
 		if ( ! is_array($key))
 		{
 			$key = array($key => $value);
@@ -292,14 +257,10 @@ class CI_DB_pdo_pgsql_driver extends CI_DB_pdo_driver {
 
 		foreach ($key as $k => $v)
 		{
-			$prefix = (count($this->qb_where) === 0 && count($this->qb_cache_where) === 0)
+			$prefix = (count($this->$qb_key) === 0 && count($this->$qb_cache_key) === 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
@@ -308,13 +269,13 @@ class CI_DB_pdo_pgsql_driver extends CI_DB_pdo_driver {
 
 			if ( ! is_null($v))
 			{
-				if ($escape === TRUE)
+				if (is_bool($v))
 				{
-					$v = ' '.$this->escape($v);
+					$v = ' '.($v ? 'TRUE' : 'FALSE');
 				}
-				elseif (is_bool($v))
+				elseif ($escape === TRUE)
 				{
-					$v = ($v ? ' TRUE' : ' FALSE');
+					$v = ' '.(is_int($v) ? $v : $this->escape($v));
 				}
 
 				if ( ! $this->_has_operator($k))
@@ -323,11 +284,11 @@ class CI_DB_pdo_pgsql_driver extends CI_DB_pdo_driver {
 				}
 			}
 
-			$this->qb_where[] = $prefix.$k.$v;
+			$this->{$qb_key}[] = array('condition' => $prefix.$k.$v, 'escape' => $escape);
 			if ($this->qb_caching === TRUE)
 			{
-				$this->qb_cache_where[] = $prefix.$k.$v;
-				$this->qb_cache_exists[] = 'where';
+				$this->{$qb_cache_key}[] = array('condition' => $prefix.$k.$v, 'escape' => $escape);
+				$this->qb_cache_exists[] = substr($qb_key, 3);
 			}
 
 		}
diff --git a/system/database/drivers/pdo/subdrivers/pdo_sqlsrv_driver.php b/system/database/drivers/pdo/subdrivers/pdo_sqlsrv_driver.php
index f125b8f50..33bd7bea5 100644
--- a/system/database/drivers/pdo/subdrivers/pdo_sqlsrv_driver.php
+++ b/system/database/drivers/pdo/subdrivers/pdo_sqlsrv_driver.php
@@ -78,9 +78,9 @@ class CI_DB_pdo_sqlsrv_driver extends CI_DB_pdo_driver {
 				$this->dsn .= ';ConnectionPooling='.$this->ConnectionPooling;
 			}
 
-			if (isset($this->Encrypt))
+			if ($this->encrypt === TRUE)
 			{
-				$this->dsn .= ';Encrypt='.$this->Encrypt;
+				$this->dsn .= ';Encrypt=1';
 			}
 
 			if (isset($this->TraceOn))
@@ -182,49 +182,19 @@ class CI_DB_pdo_sqlsrv_driver extends CI_DB_pdo_driver {
 	// --------------------------------------------------------------------
 
 	/**
-	 * 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, $like = array())
+	protected function _update($table, $values)
 	{
-		foreach ($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;
+		$this->qb_limit = FALSE;
+		$this->qb_orderby = array();
+		return parent::_update($table, $values);
 	}
 
 	// --------------------------------------------------------------------
@@ -235,23 +205,16 @@ class CI_DB_pdo_sqlsrv_driver extends CI_DB_pdo_driver {
 	 * 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(), $limit = FALSE)
+	protected function _delete($table)
 	{
-		$conditions = array();
-
-		empty($where) OR $conditions[] = implode(' ', $where);
-		empty($like) OR $conditions[] = implode(' ', $like);
-
-		$conditions = (count($conditions) > 0) ? ' WHERE '.implode(' AND ', $conditions) : '';
+		if ($this->qb_limit)
+		{
+			return 'WITH ci_delete AS (SELECT TOP '.$this->qb_limit.' * FROM '.$table.$this->_compile_wh('qb_where').') DELETE FROM ci_delete';
+		}
 
-		return ($limit)
-			? 'WITH ci_delete AS (SELECT TOP '.$limit.' * FROM '.$table.$conditions.') DELETE FROM ci_delete'
-			: 'DELETE FROM '.$table.$conditions;
+		return parent::_delete($table);
 	}
 
 	// --------------------------------------------------------------------
@@ -262,32 +225,49 @@ class CI_DB_pdo_sqlsrv_driver extends CI_DB_pdo_driver {
 	 * 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, $offset)
+	protected function _limit($sql)
 	{
 		// 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';
+			return $sql.' OFFSET '.(int) $this->qb_offset.' ROWS FETCH NEXT '.$this->qb_limit.' ROWS ONLY';
 		}
 
-		$limit = $offset + $limit;
+		$limit = $this->qb_offset + $this->qb_limit;
 
 		// An ORDER BY clause is required for ROW_NUMBER() to work
-		if ($offset && ! empty($this->qb_orderby))
+		if ($this->qb_offset && ! empty($this->qb_orderby))
 		{
-			$orderby = 'ORDER BY '.implode(', ', $this->qb_orderby);
+			$orderby = $this->_compile_order_by();
 
 			// We have to strip the ORDER BY clause
-			$sql = trim(substr($sql, 0, strrpos($sql, 'ORDER BY '.$orderby)));
+			$sql = trim(substr($sql, 0, strrpos($sql, $orderby)));
+
+			// Get the fields to select from our subquery, so that we can avoid CI_rownum appearing in the actual results
+			if (count($this->qb_select) === 0)
+			{
+				$select = '*'; // Inevitable
+			}
+			else
+			{
+				// Use only field names and their aliases, everything else is out of our scope.
+				$select = array();
+				$field_regexp = ($this->_quoted_identifier)
+					? '("[^\"]+")' : '(\[[^\]]+\])';
+				for ($i = 0, $c = count($this->qb_select); $i < $c; $i++)
+				{
+					$select[] = preg_match('/(?:\s|\.)'.$field_regexp.'$/i', $this->qb_select[$i], $m)
+						? $m[1] : $this->qb_select[$i];
+				}
+				$select = implode(', ', $select);
+			}
 
-			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 'SELECT '.$select." FROM (\n\n"
+				.preg_replace('/^(SELECT( DISTINCT)?)/i', '\\1 ROW_NUMBER() OVER('.trim($orderby).') AS '.$this->escape_identifiers('CI_rownum').', ', $sql)
+				."\n\n) ".$this->escape_identifiers('CI_subquery')
+				."\nWHERE ".$this->escape_identifiers('CI_rownum').' BETWEEN '.($this->qb_offset + 1).' AND '.$limit;
 		}
 
 		return preg_replace('/(^\SELECT (DISTINCT)?)/i','\\1 TOP '.$limit.' ', $sql);
@@ -296,4 +276,4 @@ class CI_DB_pdo_sqlsrv_driver extends CI_DB_pdo_driver {
 }
 
 /* End of file pdo_sqlsrv_driver.php */
-/* Location: ./system/database/drivers/pdo/subdrivers/pdo_sqlsrv_driver.php */
+/* Location: ./system/database/drivers/pdo/subdrivers/pdo_sqlsrv_driver.php */
\ No newline at end of file
diff --git a/system/database/drivers/postgre/postgre_driver.php b/system/database/drivers/postgre/postgre_driver.php
index 031740851..1b9474920 100644
--- a/system/database/drivers/postgre/postgre_driver.php
+++ b/system/database/drivers/postgre/postgre_driver.php
@@ -44,10 +44,6 @@ class CI_DB_postgre_driver extends CI_DB {
 
 	protected $_escape_char = '"';
 
-	// clause and character used for LIKE escape sequences
-	protected $_like_escape_str = " ESCAPE '%s' ";
-	protected $_like_escape_chr = '!';
-
 	protected $_random_keyword = ' RANDOM()'; // database specific random keyword
 
 	/**
@@ -55,6 +51,7 @@ class CI_DB_postgre_driver extends CI_DB {
 	 *
 	 * Creates a DSN string to be used for db_connect() and db_pconnect()
 	 *
+	 * @param	array	$params
 	 * @return	void
 	 */
 	public function __construct($params)
@@ -132,7 +129,15 @@ class CI_DB_postgre_driver extends CI_DB {
 	 */
 	public function db_pconnect()
 	{
-		return @pg_pconnect($this->dsn);
+		$conn = @pg_pconnect($this->dsn);
+		if ($conn && pg_connection_status($conn) === PGSQL_CONNECTION_BAD)
+		{
+			if (pg_ping($conn) === FALSE)
+			{
+				return FALSE;
+			}
+		}
+		return $conn;
 	}
 
 	// --------------------------------------------------------------------
@@ -453,49 +458,19 @@ class CI_DB_postgre_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($tables)
-	{
-		return is_array($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, $like = array())
+	protected function _update($table, $values)
 	{
-		foreach ($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;
+		$this->qb_limit = FALSE;
+		$this->qb_orderby = array();
+		return parent::_update($table, $values);
 	}
 
 	// --------------------------------------------------------------------
@@ -507,10 +482,10 @@ class CI_DB_postgre_driver extends CI_DB {
 	 *
 	 * @param	string	the table name
 	 * @param	array	the update data
-	 * @param	array	the where clause
+	 * @param	string	the where key
 	 * @return	string
 	 */
-	protected function _update_batch($table, $values, $index, $where = NULL)
+	protected function _update_batch($table, $values, $index)
 	{
 		$ids = array();
 		foreach ($values as $key => $val)
@@ -534,9 +509,9 @@ class CI_DB_postgre_driver extends CI_DB {
 				.'ELSE '.$k.' END), ';
 		}
 
-		return 'UPDATE '.$table.' SET '.substr($cases, 0, -2)
-			.' WHERE '.(($where !== '' && count($where) > 0) ? implode(' ', $where).' AND ' : '')
-			.$index.' IN('.implode(',', $ids).')';
+		$this->where($index.' IN('.implode(',', $ids).')', NULL, FALSE);
+
+		return 'UPDATE '.$table.' SET '.substr($cases, 0, -2).$this->_compile_wh('qb_where');
 	}
 
 	// --------------------------------------------------------------------
@@ -547,19 +522,12 @@ class CI_DB_postgre_driver extends CI_DB {
 	 * 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(), $limit = FALSE)
+	protected function _delete($table)
 	{
-		$conditions = array();
-
-		empty($where) OR $conditions[] = implode(' ', $where);
-		empty($like) OR $conditions[] = implode(' ', $like);
-
-		return 'DELETE FROM '.$table.(count($conditions) > 0 ? ' WHERE '.implode(' AND ', $conditions) : '');
+		$this->qb_limit = FALSE;
+		return parent::_delete($table);
 	}
 
 	// --------------------------------------------------------------------
@@ -570,30 +538,31 @@ class CI_DB_postgre_driver extends CI_DB {
 	 * 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, $offset)
+	protected function _limit($sql)
 	{
-		return $sql.' LIMIT '.$limit.($offset ? ' OFFSET '.$offset : '');
+		return $sql.' LIMIT '.$this->qb_limit.($this->qb_offset ? ' OFFSET '.$this->qb_offset : '');
 	}
 
 	// --------------------------------------------------------------------
 
 	/**
-	 * Where
+	 * WHERE, HAVING
 	 *
-	 * Called by where() or or_where()
+	 * Called by where(), or_where(), having(), or_having()
 	 *
+	 * @param	string	'qb_where' or 'qb_having'
 	 * @param	mixed
 	 * @param	mixed
 	 * @param	string
-	 * @param	mixed
+	 * @param	bool
 	 * @return	object
 	 */
-	protected function _where($key, $value = NULL, $type = 'AND ', $escape = NULL)
+	protected function _wh($qb_key, $key, $value = NULL, $type = 'AND ', $escape = NULL)
 	{
+		$qb_cache_key = ($qb_key === 'qb_having') ? 'qb_cache_having' : 'qb_cache_where';
+
 		if ( ! is_array($key))
 		{
 			$key = array($key => $value);
@@ -604,17 +573,10 @@ class CI_DB_postgre_driver extends CI_DB {
 
 		foreach ($key as $k => $v)
 		{
-			$prefix = (count($this->qb_where) === 0 && count($this->qb_cache_where) === 0)
+			$prefix = (count($this->$qb_key) === 0 && count($this->$qb_cache_key) === 0)
 				? $this->_group_get_type('')
 				: $this->_group_get_type($type);
 
-			if ($escape === TRUE)
-			{
-				$k = (($op = $this->_get_operator($k)) !== FALSE)
-					? $this->escape_identifiers(trim(substr($k, 0, strpos($k, $op)))).' '.strstr($k, $op)
-					: $this->escape_identifiers(trim($k));
-			}
-
 			if (is_null($v) && ! $this->_has_operator($k))
 			{
 				// value appears not to have been set, assign the test to IS NULL
@@ -623,13 +585,13 @@ class CI_DB_postgre_driver extends CI_DB {
 
 			if ( ! is_null($v))
 			{
-				if ($escape === TRUE)
+				if (is_bool($v))
 				{
-					$v = ' '.$this->escape($v);
+					$v = ' '.($v ? 'TRUE' : 'FALSE');
 				}
-				elseif (is_bool($v))
+				elseif ($escape === TRUE)
 				{
-					$v = ($v ? ' TRUE' : ' FALSE');
+					$v = ' '.(is_int($v) ? $v : $this->escape($v));
 				}
 
 				if ( ! $this->_has_operator($k))
@@ -638,11 +600,11 @@ class CI_DB_postgre_driver extends CI_DB {
 				}
 			}
 
-			$this->qb_where[] = $prefix.$k.$v;
+			$this->{$qb_key}[] = array('condition' => $prefix.$k.$v, 'escape' => $escape);
 			if ($this->qb_caching === TRUE)
 			{
-				$this->qb_cache_where[] = $prefix.$k.$v;
-				$this->qb_cache_exists[] = 'where';
+				$this->{$qb_cache_key}[] = array('condition' => $prefix.$k.$v, 'escape' => $escape);
+				$this->qb_cache_exists[] = substr($qb_key, 3);
 			}
 
 		}
diff --git a/system/database/drivers/postgre/postgre_forge.php b/system/database/drivers/postgre/postgre_forge.php
index c434e9510..1164d9bb3 100644
--- a/system/database/drivers/postgre/postgre_forge.php
+++ b/system/database/drivers/postgre/postgre_forge.php
@@ -39,7 +39,8 @@ class CI_DB_postgre_forge extends CI_DB_forge {
 	/**
 	 * Process Fields
 	 *
-	 * @param	mixed	the fields
+	 * @param	mixed	$fields
+	 * @param	array	$primary_keys = array()
 	 * @return	string
 	 */
 	protected function _process_fields($fields, $primary_keys = array())
@@ -190,13 +191,10 @@ class CI_DB_postgre_forge extends CI_DB_forge {
 	 * Generates a platform-specific query so that a table can be altered
 	 * Called by add_column(), drop_column(), and column_alter(),
 	 *
-	 * @param	string	the ALTER type (ADD, DROP, CHANGE)
-	 * @param	string	the column name
-	 * @param	string	the table name
-	 * @param	string	the column definition
-	 * @param	string	the default value
-	 * @param	bool	should 'NOT NULL' be added
-	 * @param	string	the field after which we should add the new field
+	 * @param	string	$alter_type	the ALTER type (ADD, DROP, CHANGE)
+	 * @param	string	$table		the table name
+	 * @param	string	$fields		the column definition
+	 * @param	string	$after_field = ''
 	 * @return	string
 	 */
 	protected function _alter_table($alter_type, $table, $fields, $after_field = '')
diff --git a/system/database/drivers/postgre/postgre_result.php b/system/database/drivers/postgre/postgre_result.php
index eb9d647e7..458ae869c 100644
--- a/system/database/drivers/postgre/postgre_result.php
+++ b/system/database/drivers/postgre/postgre_result.php
@@ -131,6 +131,7 @@ class CI_DB_postgre_result extends CI_DB_result {
 	 * this internally before fetching results to make sure the
 	 * result set starts at zero
 	 *
+	 * @param	int	$n = 0
 	 * @return	bool
 	 */
 	protected function _data_seek($n = 0)
diff --git a/system/database/drivers/sqlite/sqlite_driver.php b/system/database/drivers/sqlite/sqlite_driver.php
index 19824dbbf..2fd39346f 100644
--- a/system/database/drivers/sqlite/sqlite_driver.php
+++ b/system/database/drivers/sqlite/sqlite_driver.php
@@ -45,10 +45,6 @@ class CI_DB_sqlite_driver extends CI_DB {
 	// The character used to escape with - not needed for SQLite
 	protected $_escape_char = '"';
 
-	// clause and character used for LIKE escape sequences
-	protected $_like_escape_str = " ESCAPE '%s' ";
-	protected $_like_escape_chr = '!';
-
 	protected $_random_keyword = ' Random()'; // database specific random keyword
 
 	/**
@@ -131,6 +127,7 @@ class CI_DB_sqlite_driver extends CI_DB {
 	/**
 	 * Begin Transaction
 	 *
+	 * @param	bool	$test_mode = FALSE
 	 * @return	bool
 	 */
 	public function trans_begin($test_mode = FALSE)
diff --git a/system/database/drivers/sqlite/sqlite_result.php b/system/database/drivers/sqlite/sqlite_result.php
index eef9787a1..214841412 100644
--- a/system/database/drivers/sqlite/sqlite_result.php
+++ b/system/database/drivers/sqlite/sqlite_result.php
@@ -115,6 +115,7 @@ class CI_DB_sqlite_result extends CI_DB_result {
 	 * this internally before fetching results to make sure the
 	 * result set starts at zero
 	 *
+	 * @param	int	$n = 0
 	 * @return	bool
 	 */
 	protected function _data_seek($n = 0)
diff --git a/system/database/drivers/sqlite3/sqlite3_driver.php b/system/database/drivers/sqlite3/sqlite3_driver.php
index cc35d319f..22c72b9b8 100644
--- a/system/database/drivers/sqlite3/sqlite3_driver.php
+++ b/system/database/drivers/sqlite3/sqlite3_driver.php
@@ -46,10 +46,6 @@ class CI_DB_sqlite3_driver extends CI_DB {
 	// The character used for escaping
 	protected $_escape_char = '"';
 
-	// clause and character used for LIKE escape sequences
-	protected $_like_escape_str = ' ESCAPE \'%s\' ';
-	protected $_like_escape_chr = '!';
-
 	protected $_random_keyword = ' RANDOM()';
 
 	/**
@@ -107,13 +103,12 @@ class CI_DB_sqlite3_driver extends CI_DB {
 	/**
 	 * Execute the query
 	 *
-	 * @param	string	an SQL query
+	 * @todo	Implement use of SQLite3::querySingle(), if needed
+	 * @param	string	$sql
 	 * @return	mixed	SQLite3Result object or bool
 	 */
 	protected function _execute($sql)
 	{
-		// TODO: Implement use of SQLite3::querySingle(), if needed
-
 		return $this->is_write_type($sql)
 			? $this->conn_id->exec($sql)
 			: $this->conn_id->query($sql);
@@ -124,6 +119,7 @@ class CI_DB_sqlite3_driver extends CI_DB {
 	/**
 	 * Begin Transaction
 	 *
+	 * @param	bool	$test_mode = FALSE
 	 * @return	bool
 	 */
 	public function trans_begin($test_mode = FALSE)
@@ -288,25 +284,16 @@ class CI_DB_sqlite3_driver extends CI_DB {
 	// --------------------------------------------------------------------
 
 	/**
-	 * The error message string
+	 * Error
 	 *
-	 * @return	string
-	 */
-	protected function _error_message()
-	{
-		return $this->conn_id->lastErrorMsg();
-	}
-
-	// --------------------------------------------------------------------
-
-	/**
-	 * The error message number
+	 * Returns an array containing code and message of the last
+	 * database error that has occured.
 	 *
-	 * @return	int
+	 * @return	array
 	 */
-	protected function _error_number()
+	public function error()
 	{
-		return $this->conn_id->lastErrorCode();
+		return array('code' => $this->conn_id->lastErrorCode(), 'message' => $this->conn_id->lastErrorMsg());
 	}
 
 	// --------------------------------------------------------------------
diff --git a/system/database/drivers/sqlite3/sqlite3_result.php b/system/database/drivers/sqlite3/sqlite3_result.php
index 117fb3ce8..35aecda36 100644
--- a/system/database/drivers/sqlite3/sqlite3_result.php
+++ b/system/database/drivers/sqlite3/sqlite3_result.php
@@ -167,6 +167,7 @@ class CI_DB_sqlite3_result extends CI_DB_result {
 	 * this internally before fetching results to make sure the
 	 * result set starts at zero
 	 *
+	 * @param	$n = 0	(ignored)
 	 * @return	array
 	 */
 	protected function _data_seek($n = 0)
diff --git a/system/database/drivers/sqlsrv/sqlsrv_driver.php b/system/database/drivers/sqlsrv/sqlsrv_driver.php
index 8bd18bd76..32f1a59d6 100644
--- a/system/database/drivers/sqlsrv/sqlsrv_driver.php
+++ b/system/database/drivers/sqlsrv/sqlsrv_driver.php
@@ -45,10 +45,6 @@ class CI_DB_sqlsrv_driver extends CI_DB {
 	// The character used for escaping
 	protected $_escape_char = '"';
 
-	// clause and character used for LIKE escape sequences
-	protected $_like_escape_str = " ESCAPE '%s' ";
-	protected $_like_escape_chr = '!';
-
 	protected $_random_keyword = ' NEWID()';
 
 	// SQLSRV-specific properties
@@ -57,19 +53,21 @@ class CI_DB_sqlsrv_driver extends CI_DB {
 	/**
 	 * Non-persistent database connection
 	 *
+	 * @param	bool	$pooling = FALSE
 	 * @return	resource
 	 */
 	public function db_connect($pooling = FALSE)
 	{
-		// Check for a UTF-8 charset being passed as CI's default 'utf8'.
-		$character_set = (0 === strcasecmp('utf8', $this->char_set)) ? 'UTF-8' : $this->char_set;
+		$charset = in_array(strtolower($this->char_set), array('utf-8', 'utf8'), TRUE)
+			? 'UTF-8' : SQLSRV_ENC_CHAR;
 
 		$connection = array(
 			'UID'			=> empty($this->username) ? '' : $this->username,
 			'PWD'			=> empty($this->password) ? '' : $this->password,
 			'Database'		=> $this->database,
-			'ConnectionPooling'	=> $pooling ? 1 : 0,
-			'CharacterSet'		=> $character_set,
+			'ConnectionPooling'	=> ($pooling === TRUE) ? 1 : 0,
+			'CharacterSet'		=> $charset,
+			'Encrypt'		=> ($this->encrypt === TRUE) ? 1 : 0,
 			'ReturnDatesAsStrings'	=> 1
 		);
 
@@ -147,6 +145,7 @@ class CI_DB_sqlsrv_driver extends CI_DB {
 	/**
 	 * Begin Transaction
 	 *
+	 * @param	bool	$test_mode = FALSE
 	 * @return	bool
 	 */
 	public function trans_begin($test_mode = FALSE)
@@ -225,7 +224,7 @@ class CI_DB_sqlsrv_driver extends CI_DB {
 	 */
 	public function affected_rows()
 	{
-		return sqlrv_rows_affected($this->result_id);
+		return sqlsrv_rows_affected($this->result_id);
 	}
 
 	// --------------------------------------------------------------------
@@ -362,49 +361,19 @@ class CI_DB_sqlsrv_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($tables)
-	{
-		return is_array($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, $like = array())
+	protected function _update($table, $values)
 	{
-		foreach ($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;
+		$this->qb_limit = FALSE;
+		$this->qb_orderby = array();
+		return parent::_update($table, $values);
 	}
 
 	// --------------------------------------------------------------------
@@ -433,23 +402,16 @@ class CI_DB_sqlsrv_driver extends CI_DB {
 	 * 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(), $limit = FALSE)
+	protected function _delete($table)
 	{
-		$conditions = array();
-
-		empty($where) OR $conditions[] = implode(' ', $where);
-		empty($like) OR $conditions[] = implode(' ', $like);
-
-		$conditions = (count($conditions) > 0) ? ' WHERE '.implode(' AND ', $conditions) : '';
+		if ($this->qb_limit)
+		{
+			return 'WITH ci_delete AS (SELECT TOP '.$this->qb_limit.' * FROM '.$table.$this->_compile_wh('qb_where').') DELETE FROM ci_delete';
+		}
 
-		return ($limit)
-			? 'WITH ci_delete AS (SELECT TOP '.$limit.' * FROM '.$table.$conditions.') DELETE FROM ci_delete'
-			: 'DELETE FROM '.$table.$conditions;
+		return parent::_delete($table);
 	}
 
 	// --------------------------------------------------------------------
@@ -460,32 +422,49 @@ class CI_DB_sqlsrv_driver extends CI_DB {
 	 * 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, $offset)
+	protected function _limit($sql)
 	{
 		// 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';
+			return $sql.' OFFSET '.(int) $this->qb_offset.' ROWS FETCH NEXT '.$this->qb_limit.' ROWS ONLY';
 		}
 
-		$limit = $offset + $limit;
+		$limit = $this->qb_offset + $this->qb_limit;
 
 		// An ORDER BY clause is required for ROW_NUMBER() to work
-		if ($offset && ! empty($this->qb_orderby))
+		if ($this->qb_offset && ! empty($this->qb_orderby))
 		{
-			$orderby = 'ORDER BY '.implode(', ', $this->qb_orderby);
+			$orderby = $this->_compile_order_by();
 
 			// 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;
+			$sql = trim(substr($sql, 0, strrpos($sql, $orderby)));
+
+			// Get the fields to select from our subquery, so that we can avoid CI_rownum appearing in the actual results
+			if (count($this->qb_select) === 0)
+			{
+				$select = '*'; // Inevitable
+			}
+			else
+			{
+				// Use only field names and their aliases, everything else is out of our scope.
+				$select = array();
+				$field_regexp = ($this->_quoted_identifier)
+					? '("[^\"]+")' : '(\[[^\]]+\])';
+				for ($i = 0, $c = count($this->qb_select); $i < $c; $i++)
+				{
+					$select[] = preg_match('/(?:\s|\.)'.$field_regexp.'$/i', $this->qb_select[$i], $m)
+						? $m[1] : $this->qb_select[$i];
+				}
+				$select = implode(', ', $select);
+			}
+
+			return 'SELECT '.$select." FROM (\n\n"
+				.preg_replace('/^(SELECT( DISTINCT)?)/i', '\\1 ROW_NUMBER() OVER('.trim($orderby).') AS '.$this->escape_identifiers('CI_rownum').', ', $sql)
+				."\n\n) ".$this->escape_identifiers('CI_subquery')
+				."\nWHERE ".$this->escape_identifiers('CI_rownum').' BETWEEN '.($this->qb_offset + 1).' AND '.$limit;
 		}
 
 		return preg_replace('/(^\SELECT (DISTINCT)?)/i','\\1 TOP '.$limit.' ', $sql);