23 files changed, 347 insertions, 297 deletions
diff --git a/phpBB/includes/acm/acm_file.php b/phpBB/includes/acm/acm_file.php
index fa6e79260b..3be4483774 100644
--- a/phpBB/includes/acm/acm_file.php
+++ b/phpBB/includes/acm/acm_file.php
@@ -88,7 +88,7 @@ class acm
 		if ($fp = @fopen($this->cache_dir . 'data_global.' . $phpEx, 'wb'))
 		{
 			@flock($fp, LOCK_EX);
-			fwrite($fp, "<?php\n\$this->vars = " . var_export($this->vars, true) . ";\n\n\$this->var_expires = " . var_export($this->var_expires, true) . "\n?>");
+			fwrite($fp, "<?php\n\$this->vars = unserialize('" . serialize($this->vars) . "');\n\$this->var_expires = unserialize('" . serialize($this->var_expires) . "');");
 			@flock($fp, LOCK_UN);
 			fclose($fp);
 
@@ -192,7 +192,7 @@ class acm
 			if ($fp = @fopen($this->cache_dir . "data{$var_name}.$phpEx", 'wb'))
 			{
 				@flock($fp, LOCK_EX);
-				fwrite($fp, "<?php\n\$expired = (time() > " . (time() + $ttl) . ") ? true : false;\nif (\$expired) { return; }\n\n\$data = " . var_export($var, true) . ";\n?>");
+				fwrite($fp, "<?php\n\$expired = (time() > " . (time() + $ttl) . ") ? true : false;\nif (\$expired) { return; }\n\$data =  " . (sizeof($var) ? "unserialize('" . serialize($var) . "');" : 'array();'));
 				@flock($fp, LOCK_UN);
 				fclose($fp);
 
@@ -210,7 +210,7 @@ class acm
 	/**
 	* Purge cache data
 	*/
-	function purge()
+	public function purge()
 	{
 		// Purge all phpbb cache files
 		$dir = @opendir($this->cache_dir);
@@ -247,7 +247,7 @@ class acm
 	/**
 	* Destroy cache data
 	*/
-	function destroy($var_name, $table = '')
+	public function destroy($var_name, $table = '')
 	{
 		global $phpEx;
 
@@ -327,7 +327,7 @@ class acm
 	/**
 	* Check if a given cache entry exist
 	*/
-	function _exists($var_name)
+	private function _exists($var_name)
 	{
 		if ($var_name[0] === '_')
 		{
@@ -353,7 +353,7 @@ class acm
 	/**
 	* Load cached sql query
 	*/
-	function sql_load($query)
+	public function sql_load($query)
 	{
 		global $phpEx;
 
@@ -386,7 +386,7 @@ class acm
 	/**
 	* Save sql query
 	*/
-	function sql_save($query, &$query_result, $ttl)
+	public function sql_save($query, &$query_result, $ttl)
 	{
 		global $db, $phpEx;
 
@@ -408,10 +408,10 @@ class acm
 			}
 			$db->sql_freeresult($query_result);
 
-			$file = "<?php\n\n/* " . str_replace('*/', '*\/', $query) . " */\n";
+			$file = "<?php\n/* " . str_replace('*/', '*\/', $query) . " */";
 			$file .= "\n\$expired = (time() > " . (time() + $ttl) . ") ? true : false;\nif (\$expired) { return; }\n";
 
-			fwrite($fp, $file . "\n\$this->sql_rowset[\$query_id] = " . var_export($this->sql_rowset[$query_id], true) . ";\n?>");
+			fwrite($fp, $file . "\$this->sql_rowset[\$query_id] = " . (sizeof($this->sql_rowset[$query_id]) ? "unserialize('" . serialize($this->sql_rowset[$query_id]) . "');" : 'array();'));
 			@flock($fp, LOCK_UN);
 			fclose($fp);
 
@@ -422,17 +422,9 @@ class acm
 	}
 
 	/**
-	* Ceck if a given sql query exist in cache
-	*/
-	function sql_exists($query_id)
-	{
-		return isset($this->sql_rowset[$query_id]);
-	}
-
-	/**
 	* Fetch row from cache (database)
 	*/
-	function sql_fetchrow($query_id)
+	public function sql_fetchrow($query_id)
 	{
 		if ($this->sql_row_pointer[$query_id] < sizeof($this->sql_rowset[$query_id]))
 		{
@@ -445,7 +437,7 @@ class acm
 	/**
 	* Fetch a field from the current row of a cached database result (database)
 	*/
-	function sql_fetchfield($query_id, $field)
+	public function sql_fetchfield($query_id, $field)
 	{
 		if ($this->sql_row_pointer[$query_id] < sizeof($this->sql_rowset[$query_id]))
 		{
@@ -458,7 +450,7 @@ class acm
 	/**
 	* Seek a specific row in an a cached database result (database)
 	*/
-	function sql_rowseek($rownum, $query_id)
+	public function sql_rowseek($rownum, $query_id)
 	{
 		if ($rownum >= sizeof($this->sql_rowset[$query_id]))
 		{
@@ -472,7 +464,7 @@ class acm
 	/**
 	* Free memory used for a cached database result (database)
 	*/
-	function sql_freeresult($query_id)
+	public function sql_freeresult($query_id)
 	{
 		if (!isset($this->sql_rowset[$query_id]))
 		{
@@ -488,7 +480,7 @@ class acm
 	/**
 	* Removes/unlinks file
 	*/
-	function remove_file($filename)
+	private function remove_file($filename)
 	{
 		if (!@unlink($filename))
 		{
diff --git a/phpBB/includes/acp/acp_icons.php b/phpBB/includes/acp/acp_icons.php
index 537c0425a2..b4ac697a52 100644
--- a/phpBB/includes/acp/acp_icons.php
+++ b/phpBB/includes/acp/acp_icons.php
@@ -477,16 +477,12 @@ class acp_icons
 					// The user has already selected a smilies_pak file
 					if ($current == 'delete')
 					{
-						switch ($db->sql_layer)
+						if ($db->truncate)
 						{
-							case 'sqlite':
-							case 'firebird':
-								$db->sql_query('DELETE FROM ' . $table);
-							break;
-
-							default:
-								$db->sql_query('TRUNCATE TABLE ' . $table);
-							break;
+							$db->sql_query('TRUNCATE TABLE ' . $table);
+						else
+						{
+							$db->sql_query('DELETE FROM ' . $table);
 						}
 
 						switch ($mode)
diff --git a/phpBB/includes/acp/acp_main.php b/phpBB/includes/acp/acp_main.php
index d41e1f4a62..ca3ac20630 100644
--- a/phpBB/includes/acp/acp_main.php
+++ b/phpBB/includes/acp/acp_main.php
@@ -202,16 +202,12 @@ class acp_main
 					break;
 				
 					case 'db_track':
-						switch ($db->sql_layer)
+						if ($db->truncate)
 						{
-							case 'sqlite':
-							case 'firebird':
-								$db->sql_query('DELETE FROM ' . TOPICS_POSTED_TABLE);
-							break;
-
-							default:
-								$db->sql_query('TRUNCATE TABLE ' . TOPICS_POSTED_TABLE);
-							break;
+							$db->sql_query('TRUNCATE TABLE ' . TOPICS_POSTED_TABLE);
+						else
+						{
+							$db->sql_query('DELETE FROM ' . TOPICS_POSTED_TABLE);
 						}
 
 						// This can get really nasty... therefore we only do the last six months
diff --git a/phpBB/includes/acp/acp_reasons.php b/phpBB/includes/acp/acp_reasons.php
index 8d7bc88769..80c8e5323d 100644
--- a/phpBB/includes/acp/acp_reasons.php
+++ b/phpBB/includes/acp/acp_reasons.php
@@ -211,53 +211,22 @@ class acp_reasons
 				// Let the deletion be confirmed...
 				if (confirm_box(true))
 				{
-					$sql = 'SELECT reason_id
+					$sql = 'SELECT reason_id, report_text
 						FROM ' . REPORTS_REASONS_TABLE . "
 						WHERE LOWER(reason_title) = 'other'";
 					$result = $db->sql_query($sql);
-					$other_reason_id = (int) $db->sql_fetchfield('reason_id');
+					$row = $db->sql_fetchrow($result);
+
+					$other_reason_id = (int) $row['reason_id'];
+					$report_text = $row['report_text'];
+
 					$db->sql_freeresult($result);
 
-					switch ($db->sql_layer)
-					{
-						// The ugly one!
-						case 'mysqli':
-						case 'mysql4':
-						case 'mysql':
-							// Change the reports using this reason to 'other'
-							$sql = 'UPDATE ' . REPORTS_TABLE . '
-								SET reason_id = ' . $other_reason_id . ", report_text = CONCAT('" . $db->sql_escape($reason_row['reason_description']) . "\n\n', report_text)
-								WHERE reason_id = $reason_id";
-						break;
-
-						// Standard? What's that?
-						case 'mssql':
-						case 'mssql_odbc':
-							// Change the reports using this reason to 'other'
-							$sql = "DECLARE @ptrval binary(16)
-
-									SELECT @ptrval = TEXTPTR(report_text)
-										FROM " . REPORTS_TABLE . "
-									WHERE reason_id = " . $reason_id . "
-
-									UPDATETEXT " . REPORTS_TABLE . ".report_text @ptrval 0 0 '" . $db->sql_escape($reason_row['reason_description']) . "\n\n'
-
-									UPDATE " . REPORTS_TABLE . '
-										SET reason_id = ' . $other_reason_id . "
-									WHERE reason_id = $reason_id";
-						break;
-
-						// Teh standard
-						case 'postgres':
-						case 'oracle':
-						case 'firebird':
-						case 'sqlite':
-							// Change the reports using this reason to 'other'
-							$sql = 'UPDATE ' . REPORTS_TABLE . '
-								SET reason_id = ' . $other_reason_id . ", report_text = '" . $db->sql_escape($reason_row['reason_description']) . "\n\n' || report_text
-								WHERE reason_id = $reason_id";
-						break;
-					}
+					$report_text .= $reason_row['reason_description'] . "\n\n";
+
+					$sql = 'UPDATE ' . REPORTS_TABLE . '
+						SET reason_id = ' . $other_reason_id . ", report_text = '" . $db->sql_escape($report_text) "'
+						WHERE reason_id = $reason_id";
 					$db->sql_query($sql);
 
 					$db->sql_query('DELETE FROM ' . REPORTS_REASONS_TABLE . ' WHERE reason_id = ' . $reason_id);
diff --git a/phpBB/includes/cache.php b/phpBB/includes/cache.php
index 52e0007b28..c5445e7a56 100644
--- a/phpBB/includes/cache.php
+++ b/phpBB/includes/cache.php
@@ -295,31 +295,10 @@ class cache
 		{
 			global $db;
 
-			switch ($db->sql_layer)
-			{
-				case 'mssql':
-				case 'mssql_odbc':
-					$sql = 'SELECT user_id, bot_agent, bot_ip
-						FROM ' . BOTS_TABLE . '
-						WHERE bot_active = 1
-					ORDER BY LEN(bot_agent) DESC';
-				break;
-
-				case 'firebird':
-					$sql = 'SELECT user_id, bot_agent, bot_ip
-						FROM ' . BOTS_TABLE . '
-						WHERE bot_active = 1
-					ORDER BY CHAR_LENGTH(bot_agent) DESC';
-				break;
-
-				// LENGTH supported by MySQL, IBM DB2 and Oracle for sure...
-				default:
-					$sql = 'SELECT user_id, bot_agent, bot_ip
-						FROM ' . BOTS_TABLE . '
-						WHERE bot_active = 1
-					ORDER BY LENGTH(bot_agent) DESC';
-				break;
-			}
+			$sql = 'SELECT user_id, bot_agent, bot_ip
+				FROM ' . BOTS_TABLE . '
+				WHERE bot_active = 1
+			ORDER BY ' . $db->sql_function('length_varchar', 'bot_agent') . 'DESC';
 			$result = $db->sql_query($sql);
 
 			$bots = array();
diff --git a/phpBB/includes/db/dbal.php b/phpBB/includes/db/dbal.php
index a2a42e173c..d22d2f0520 100644
--- a/phpBB/includes/db/dbal.php
+++ b/phpBB/includes/db/dbal.php
@@ -52,6 +52,15 @@ class dbal
 	// Supports multi inserts?
 	var $multi_insert = false;
 
+	// Supports COUNT(DISTINCT ...)?
+	var $count_distinct = true;
+
+	// Supports multiple table deletion
+	var $multi_table_deletion = false;
+
+	// Supports table truncation
+	var $truncate = true;
+
 	/**
 	* Current sql layer
 	*/
diff --git a/phpBB/includes/db/firebird.php b/phpBB/includes/db/firebird.php
index b258b96fa1..21dd6f0127 100644
--- a/phpBB/includes/db/firebird.php
+++ b/phpBB/includes/db/firebird.php
@@ -28,6 +28,9 @@ class dbal_firebird extends dbal
 	var $last_query_text = '';
 	var $service_handle = false;
 
+	// can't truncate a table
+	var $truncate = false;
+
 	/**
 	* Connect to server
 	*/
@@ -377,6 +380,20 @@ class dbal_firebird extends dbal
 	}
 
 	/**
+	* Expose a DBMS specific function
+	*/
+	function sql_function($type, $col)
+	{
+		switch ($type)
+		{
+			case 'length_varchar':
+			case 'length_text':
+				return 'OCTET_LENGTH(' . $col . ')';
+			break;
+		}
+	}
+
+	/**
 	* Build LIKE expression
 	* @access private
 	*/
diff --git a/phpBB/includes/db/mssql.php b/phpBB/includes/db/mssql.php
index 1e42abcce2..f89fcb9d8f 100644
--- a/phpBB/includes/db/mssql.php
+++ b/phpBB/includes/db/mssql.php
@@ -309,6 +309,20 @@ class dbal_mssql extends dbal
 	}
 
 	/**
+	* Expose a DBMS specific function
+	*/
+	function sql_function($type, $col)
+	{
+		switch ($type)
+		{
+			case 'length_varchar':
+			case 'length_text':
+				return 'DATALENGTH(' . $col . ')';
+			break;
+		}
+	}
+
+	/**
 	* Build LIKE expression
 	* @access private
 	*/
diff --git a/phpBB/includes/db/mssql_odbc.php b/phpBB/includes/db/mssql_odbc.php
index 7722f79952..5ef00c6839 100644
--- a/phpBB/includes/db/mssql_odbc.php
+++ b/phpBB/includes/db/mssql_odbc.php
@@ -337,6 +337,20 @@ class dbal_mssql_odbc extends dbal
 	}
 
 	/**
+	* Expose a DBMS specific function
+	*/
+	function sql_function($type, $col)
+	{
+		switch ($type)
+		{
+			case 'length_varchar':
+			case 'length_text':
+				return 'DATALENGTH(' . $col . ')';
+			break;
+		}
+	}
+
+	/**
 	* Build LIKE expression
 	* @access private
 	*/
diff --git a/phpBB/includes/db/mysql.php b/phpBB/includes/db/mysql.php
index 840d40b03d..108a75c0cc 100644
--- a/phpBB/includes/db/mysql.php
+++ b/phpBB/includes/db/mysql.php
@@ -32,6 +32,9 @@ class dbal_mysql extends dbal
 	var $mysql_version;
 	var $multi_insert = true;
 
+	// Supports multiple table deletion
+	var $multi_table_deletion = false;
+
 	/**
 	* Connect to server
 	* @access public
@@ -302,6 +305,20 @@ class dbal_mysql extends dbal
 	}
 
 	/**
+	* Expose a DBMS specific function
+	*/
+	function sql_function($type, $col)
+	{
+		switch ($type)
+		{
+			case 'length_varchar':
+			case 'length_text':
+				return 'LENGTH(' . $col . ')';
+			break;
+		}
+	}
+
+	/**
 	* Build LIKE expression
 	* @access private
 	*/
diff --git a/phpBB/includes/db/mysqli.php b/phpBB/includes/db/mysqli.php
index 32765d15f7..394c547151 100644
--- a/phpBB/includes/db/mysqli.php
+++ b/phpBB/includes/db/mysqli.php
@@ -28,6 +28,9 @@ class dbal_mysqli extends dbal
 {
 	var $multi_insert = true;
 
+	// Supports multiple table deletion
+	var $multi_table_deletion = false;
+
 	/**
 	* Connect to server
 	*/
@@ -271,6 +274,20 @@ class dbal_mysqli extends dbal
 	}
 
 	/**
+	* Expose a DBMS specific function
+	*/
+	function sql_function($type, $col)
+	{
+		switch ($type)
+		{
+			case 'length_varchar':
+			case 'length_text':
+				return 'LENGTH(' . $col . ')';
+			break;
+		}
+	}
+
+	/**
 	* Build LIKE expression
 	* @access private
 	*/
diff --git a/phpBB/includes/db/oracle.php b/phpBB/includes/db/oracle.php
index 18740fb036..0640d3d354 100644
--- a/phpBB/includes/db/oracle.php
+++ b/phpBB/includes/db/oracle.php
@@ -534,6 +534,23 @@ class dbal_oracle extends dbal
 	}
 
 	/**
+	* Expose a DBMS specific function
+	*/
+	function sql_function($type, $col)
+	{
+		switch ($type)
+		{
+			case 'length_varchar':
+				return 'LENGTH(' . $col . ')';
+			break;
+
+			case 'length_text':
+				return 'dbms_lob.getlength(' . $col . ')';
+			break;
+		}
+	}
+
+	/**
 	* Build LIKE expression
 	* @access private
 	*/
diff --git a/phpBB/includes/db/postgres.php b/phpBB/includes/db/postgres.php
index 0ac27023f3..0f946c2d7c 100644
--- a/phpBB/includes/db/postgres.php
+++ b/phpBB/includes/db/postgres.php
@@ -27,7 +27,7 @@ class dbal_postgres extends dbal
 {
 	var $last_query_text = '';
 	var $pgsql_version;
-	
+
 	/**
 	* Connect to server
 	*/
@@ -84,9 +84,17 @@ class dbal_postgres extends dbal
 			// determine what version of PostgreSQL is running, we can be more efficient if they are running 8.2+
 			$this->pgsql_version = @pg_parameter_status($this->db_connect_id, 'server_version');
 
-			if (!empty($this->pgsql_version) && $this->pgsql_version[0] >= '8' && $this->pgsql_version[2] >= '2')
+			if (!empty($this->pgsql_version) && $this->pgsql_version[0] >= '8')
 			{
-				$this->multi_insert = true;
+				if ($this->pgsql_version[2] >= '1')
+				{
+					$this->multi_table_deletion = true;
+				}
+
+				if ($this->pgsql_version[2] >= '2')
+				{
+					$this->multi_insert = true;
+				}
 			}
 
 			if ($schema !== '')
@@ -332,6 +340,20 @@ class dbal_postgres extends dbal
 	}
 
 	/**
+	* Expose a DBMS specific function
+	*/
+	function sql_function($type, $col)
+	{
+		switch ($type)
+		{
+			case 'length_varchar':
+			case 'length_text':
+				return 'LENGTH(' . $col . ')';
+			break;
+		}
+	}
+
+	/**
 	* Build LIKE expression
 	* @access private
 	*/
diff --git a/phpBB/includes/db/sqlite.php b/phpBB/includes/db/sqlite.php
index 5ae36df4f5..c6f6f8fc9b 100644
--- a/phpBB/includes/db/sqlite.php
+++ b/phpBB/includes/db/sqlite.php
@@ -25,6 +25,12 @@ include_once($phpbb_root_path . 'includes/db/dbal.' . $phpEx);
 */
 class dbal_sqlite extends dbal
 {
+	// like MS ACCESS, SQLite does not support COUNT(DISTINCT ...)
+	var $count_distinct = false;
+
+	// can't truncate a table
+	var $truncate = false;
+
 	/**
 	* Connect to server
 	*/
@@ -258,6 +264,20 @@ class dbal_sqlite extends dbal
 	}
 
 	/**
+	* Expose a DBMS specific function
+	*/
+	function sql_function($type, $col)
+	{
+		switch ($type)
+		{
+			case 'length_varchar':
+			case 'length_text':
+				return 'LENGTH(' . $col . ')';
+			break;
+		}
+	}
+
+	/**
 	* return sql error array
 	* @access private
 	*/
diff --git a/phpBB/includes/functions.php b/phpBB/includes/functions.php
index 63a90ee9cc..84fd033ddb 100644
--- a/phpBB/includes/functions.php
+++ b/phpBB/includes/functions.php
@@ -3007,7 +3007,15 @@ function page_header($page_title = '', $display_online_list = true)
 		// Get number of online guests
 		if (!$config['load_online_guests'])
 		{
-			if ($db->sql_layer === 'sqlite')
+			if ($db->count_distinct)
+			{
+				$sql = 'SELECT COUNT(DISTINCT s.session_ip) as num_guests
+					FROM ' . SESSIONS_TABLE . ' s
+					WHERE s.session_user_id = ' . ANONYMOUS . '
+						AND s.session_time >= ' . (time() - ($config['load_online_time'] * 60)) .
+					$reading_sql;
+			}
+			else
 			{
 				$sql = 'SELECT COUNT(session_ip) as num_guests
 					FROM (
@@ -3018,14 +3026,6 @@ function page_header($page_title = '', $display_online_list = true)
 								$reading_sql .
 					')';
 			}
-			else
-			{
-				$sql = 'SELECT COUNT(DISTINCT s.session_ip) as num_guests
-					FROM ' . SESSIONS_TABLE . ' s
-					WHERE s.session_user_id = ' . ANONYMOUS . '
-						AND s.session_time >= ' . (time() - ($config['load_online_time'] * 60)) .
-					$reading_sql;
-			}
 			$result = $db->sql_query($sql);
 			$guests_online = (int) $db->sql_fetchfield('num_guests');
 			$db->sql_freeresult($result);
diff --git a/phpBB/includes/functions_admin.php b/phpBB/includes/functions_admin.php
index 268eccbca4..b4410bcce1 100644
--- a/phpBB/includes/functions_admin.php
+++ b/phpBB/includes/functions_admin.php
@@ -1004,40 +1004,38 @@ function delete_topic_shadows($max_age, $forum_id = '', $auto_sync = true)
 {
 	$where = (is_array($forum_id)) ? 'AND ' . $db->sql_in_set('t.forum_id', array_map('intval', $forum_id)) : (($forum_id) ? 'AND t.forum_id = ' . (int) $forum_id : '');
 
-	switch ($db->sql_layer)
+	if ($db->multi_table_deletion)
 	{
-		case 'mysql4':
-		case 'mysqli':
-			$sql = 'DELETE t.*
-				FROM ' . TOPICS_TABLE . ' t, ' . TOPICS_TABLE . ' t2
+			$sql = 'DELETE FROM ' . TOPICS_TABLE . ' t
+				USING ' . TOPICS_TABLE . ' t2
 				WHERE t.topic_moved_id = t2.topic_id
 					AND t.topic_time < ' . (time() - $max_age)
-				. $where;
+					. $where;
 			$db->sql_query($sql);
-		break;
-	
-		default:
-			$sql = 'SELECT t.topic_id
-				FROM ' . TOPICS_TABLE . ' t, ' . TOPICS_TABLE . ' t2
-				WHERE t.topic_moved_id = t2.topic_id
-					AND t.topic_time < ' . (time() - $max_age)
-				. $where;
-			$result = $db->sql_query($sql);
 
-			$topic_ids = array();
-			while ($row = $db->sql_fetchrow($result))
-			{
-				$topic_ids[] = $row['topic_id'];
-			}
-			$db->sql_freeresult($result);
+	}
+	else
+	{
+		$sql = 'SELECT t.topic_id
+			FROM ' . TOPICS_TABLE . ' t, ' . TOPICS_TABLE . ' t2
+			WHERE t.topic_moved_id = t2.topic_id
+				AND t.topic_time < ' . (time() - $max_age)
+			. $where;
+		$result = $db->sql_query($sql);
 
-			if (sizeof($topic_ids))
-			{
-				$sql = 'DELETE FROM ' . TOPICS_TABLE . '
-					WHERE ' . $db->sql_in_set('topic_id', $topic_ids);
-				$db->sql_query($sql);
-			}
-		break;
+		$topic_ids = array();
+		while ($row = $db->sql_fetchrow($result))
+		{
+			$topic_ids[] = $row['topic_id'];
+		}
+		$db->sql_freeresult($result);
+
+		if (sizeof($topic_ids))
+		{
+			$sql = 'DELETE FROM ' . TOPICS_TABLE . '
+				WHERE ' . $db->sql_in_set('topic_id', $topic_ids);
+			$db->sql_query($sql);
+		}
 	}
 
 	if ($auto_sync)
@@ -1203,41 +1201,37 @@ function sync($mode, $where_type = '', $where_ids = '', $resync_parents = false,
 	switch ($mode)
 	{
 		case 'topic_moved':
-			switch ($db->sql_layer)
+			if ($db->multi_table_deletion)
 			{
-				case 'mysql4':
-				case 'mysqli':
-					$sql = 'DELETE FROM ' . TOPICS_TABLE . '
-						USING ' . TOPICS_TABLE . ' t1, ' . TOPICS_TABLE . " t2
-						WHERE t1.topic_moved_id = t2.topic_id
-							AND t1.forum_id = t2.forum_id";
-					$db->sql_query($sql);
-				break;
-			
-				default:
-					$sql = 'SELECT t1.topic_id
-						FROM ' .TOPICS_TABLE . ' t1, ' . TOPICS_TABLE . " t2
-						WHERE t1.topic_moved_id = t2.topic_id
-							AND t1.forum_id = t2.forum_id";
-					$result = $db->sql_query($sql);
-
-					$topic_id_ary = array();
-					while ($row = $db->sql_fetchrow($result))
-					{
-						$topic_id_ary[] = $row['topic_id'];
-					}
-					$db->sql_freeresult($result);
+				$sql = 'DELETE FROM ' . TOPICS_TABLE . '
+					USING ' . TOPICS_TABLE . ' t1, ' . TOPICS_TABLE . " t2
+					WHERE t1.topic_moved_id = t2.topic_id
+						AND t1.forum_id = t2.forum_id";
+				$db->sql_query($sql);
+			}
+			else
+			{
+				$sql = 'SELECT t1.topic_id
+					FROM ' .TOPICS_TABLE . ' t1, ' . TOPICS_TABLE . " t2
+					WHERE t1.topic_moved_id = t2.topic_id
+						AND t1.forum_id = t2.forum_id";
+				$result = $db->sql_query($sql);
 
-					if (!sizeof($topic_id_ary))
-					{
-						return;
-					}
+				$topic_id_ary = array();
+				while ($row = $db->sql_fetchrow($result))
+				{
+					$topic_id_ary[] = $row['topic_id'];
+				}
+				$db->sql_freeresult($result);
 
-					$sql = 'DELETE FROM ' . TOPICS_TABLE . '
-						WHERE ' . $db->sql_in_set('topic_id', $topic_id_ary);
-					$db->sql_query($sql);
+				if (!sizeof($topic_id_ary))
+				{
+					return;
+				}
 
-				break;
+				$sql = 'DELETE FROM ' . TOPICS_TABLE . '
+					WHERE ' . $db->sql_in_set('topic_id', $topic_id_ary);
+				$db->sql_query($sql);
 			}
 		break;
 
@@ -2167,16 +2161,12 @@ function cache_moderators()
 	$cache->destroy('sql', MODERATOR_CACHE_TABLE);
 
 	// Clear table
-	switch ($db->sql_layer)
+	if ($db->truncate)
 	{
-		case 'sqlite':
-		case 'firebird':
-			$db->sql_query('DELETE FROM ' . MODERATOR_CACHE_TABLE);
-		break;
-
-		default:
-			$db->sql_query('TRUNCATE TABLE ' . MODERATOR_CACHE_TABLE);
-		break;
+		$db->sql_query('TRUNCATE TABLE ' . MODERATOR_CACHE_TABLE);
+	else
+	{
+		$db->sql_query('DELETE FROM ' . MODERATOR_CACHE_TABLE);
 	}
 
 	// We add moderators who have forum moderator permissions without an explicit ACL_NEVER setting
@@ -2609,39 +2599,36 @@ function update_foes($group_id = false, $user_id = false)
 			return;
 		}
 
-		switch ($db->sql_layer)
+		if ($db->multi_table_deletion)
 		{
-			case 'mysqli':
-			case 'mysql4':
-				$sql = 'DELETE ' . (($db->sql_layer === 'mysqli' || version_compare($db->mysql_version, '4.1', '>=')) ? 'z.*' : ZEBRA_TABLE) . '
-					FROM ' . ZEBRA_TABLE . ' z, ' . USER_GROUP_TABLE . ' ug
-					WHERE z.zebra_id = ug.user_id
-						AND z.foe = 1
-						AND ' . $db->sql_in_set('ug.group_id', $groups);
-				$db->sql_query($sql);
-			break;
-
-			default:
-				$sql = 'SELECT user_id
-					FROM ' . USER_GROUP_TABLE . '
-					WHERE ' . $db->sql_in_set('group_id', $groups);
-				$result = $db->sql_query($sql);
+			$sql = 'DELETE FROM' . ZEBRA_TABLE . ' z
+				USING ' . USER_GROUP_TABLE . ' ug
+				WHERE z.zebra_id = ug.user_id
+					AND z.foe = 1
+					AND ' . $db->sql_in_set('ug.group_id', $groups);
+			$db->sql_query($sql);
+		}
+		else
+		{
+			$sql = 'SELECT user_id
+				FROM ' . USER_GROUP_TABLE . '
+				WHERE ' . $db->sql_in_set('group_id', $groups);
+			$result = $db->sql_query($sql);
 
-				$users = array();
-				while ($row = $db->sql_fetchrow($result))
-				{
-					$users[] = (int) $row['user_id'];
-				}
-				$db->sql_freeresult($result);
+			$users = array();
+			while ($row = $db->sql_fetchrow($result))
+			{
+				$users[] = (int) $row['user_id'];
+			}
+			$db->sql_freeresult($result);
 
-				if (sizeof($users))
-				{				
-					$sql = 'DELETE FROM ' . ZEBRA_TABLE . '
-						WHERE ' . $db->sql_in_set('zebra_id', $users) . '
-							AND foe = 1';
-					$db->sql_query($sql);
-				}
-			break;
+			if (sizeof($users))
+			{				
+				$sql = 'DELETE FROM ' . ZEBRA_TABLE . '
+					WHERE ' . $db->sql_in_set('zebra_id', $users) . '
+						AND foe = 1';
+				$db->sql_query($sql);
+			}
 		}
 
 		return;
diff --git a/phpBB/includes/mcp/mcp_forum.php b/phpBB/includes/mcp/mcp_forum.php
index 1cba3157d7..3bc4e9cf03 100644
--- a/phpBB/includes/mcp/mcp_forum.php
+++ b/phpBB/includes/mcp/mcp_forum.php
@@ -146,8 +146,8 @@ function mcp_forum_view($id, $mode, $action, $forum_info)
 		$read_tracking_join = $read_tracking_select = '';
 	}
 
-	$sql = "SELECT t.*$read_tracking_select
-		FROM " . TOPICS_TABLE . " t $read_tracking_join
+	$sql = "SELECT t.topic_id
+		FROM " . TOPICS_TABLE . " t
 		WHERE t.forum_id IN($forum_id, 0)
 			" . (($auth->acl_get('m_approve', $forum_id)) ? '' : 'AND t.topic_approved = 1') . "
 			$limit_time_sql
@@ -155,13 +155,24 @@ function mcp_forum_view($id, $mode, $action, $forum_info)
 	$result = $db->sql_query_limit($sql, $topics_per_page, $start);
 
 	$topic_list = $topic_tracking_info = array();
+
 	while ($row = $db->sql_fetchrow($result))
 	{
-		$topic_rows[$row['topic_id']] = $row;
 		$topic_list[] = $row['topic_id'];
 	}
 	$db->sql_freeresult($result);
 
+	$sql = "SELECT t.*$read_tracking_select
+		FROM " . TOPICS_TABLE . " t $read_tracking_join
+		WHERE " . $db->sql_in_set('t.topic_id', $topic_list);
+
+	$result = $db->sql_query($sql);
+	while ($row = $db->sql_fetchrow($result))
+	{
+		$topic_rows[$row['topic_id']] = $row;
+	}
+	$db->sql_freeresult($result);
+
 	// If there is more than one page, but we have no topic list, then the start parameter is... erm... out of sync
 	if (!sizeof($topic_list) && $forum_topics && $start > 0)
 	{
@@ -181,10 +192,12 @@ function mcp_forum_view($id, $mode, $action, $forum_info)
 		}
 	}
 
-	foreach ($topic_rows as $topic_id => $row)
+	foreach ($topic_list as $topic_id)
 	{
 		$topic_title = '';
 
+		$row = &$topic_rows[$topic_id];
+
 		$replies = ($auth->acl_get('m_approve', $forum_id)) ? $row['topic_replies_real'] : $row['topic_replies'];
 
 		if ($row['topic_status'] == ITEM_MOVED)
diff --git a/phpBB/includes/message_parser.php b/phpBB/includes/message_parser.php
index 6e601e1499..82755b1f15 100644
--- a/phpBB/includes/message_parser.php
+++ b/phpBB/includes/message_parser.php
@@ -1251,28 +1251,10 @@ class parse_message extends bbcode_firstpass
 			// NOTE: obtain_* function? chaching the table contents?
 	
 			// For now setting the ttl to 10 minutes
-			switch ($db->sql_layer)
-			{
-				case 'mssql':
-				case 'mssql_odbc':
-					$sql = 'SELECT *
-						FROM ' . SMILIES_TABLE . '
-						ORDER BY LEN(code) DESC';
-				break;
-	
-				case 'firebird':
-					$sql = 'SELECT *
-						FROM ' . SMILIES_TABLE . '
-						ORDER BY CHAR_LENGTH(code) DESC';
-				break;
-
-				// LENGTH supported by MySQL, IBM DB2, Oracle and Access for sure...
-				default:
-					$sql = 'SELECT *
-						FROM ' . SMILIES_TABLE . '
-						ORDER BY LENGTH(code) DESC';
-				break;
-			}
+			$sql = 'SELECT *
+				FROM ' . SMILIES_TABLE . '
+				ORDER BY ' . $db->sql_function('length_varchar', 'code') . ' DESC';
+
 			$result = $db->sql_query($sql, 600);
 
 			while ($row = $db->sql_fetchrow($result))
diff --git a/phpBB/includes/search/fulltext_native.php b/phpBB/includes/search/fulltext_native.php
index 89689151fe..788af4b002 100755
--- a/phpBB/includes/search/fulltext_native.php
+++ b/phpBB/includes/search/fulltext_native.php
@@ -864,14 +864,14 @@ class fulltext_native extends search_backend
 					}
 					else
 					{
-						if ($db->sql_layer == 'sqlite')
+						if ($db->count_distinct)
 						{
-							$sql = 'SELECT COUNT(topic_id) as total_results
-								FROM (SELECT DISTINCT t.topic_id';
+							$sql = 'SELECT COUNT(DISTINCT t.topic_id) as total_results';
 						}
 						else
 						{
-							$sql = 'SELECT COUNT(DISTINCT t.topic_id) as total_results';
+							$sql = 'SELECT COUNT(topic_id) as total_results
+								FROM (SELECT DISTINCT t.topic_id';
 						}
 
 						$sql .= ' FROM ' . TOPICS_TABLE . ' t, ' . POSTS_TABLE . " p
@@ -881,7 +881,7 @@ class fulltext_native extends search_backend
 								$m_approve_fid_sql
 								$sql_fora
 								AND t.topic_id = p.topic_id
-								$sql_time" . (($db->sql_layer == 'sqlite') ? ')' : '');
+								$sql_time" . (($db->count_distinct) ? '' : ')');
 					}
 					$result = $db->sql_query($sql);
 
diff --git a/phpBB/search.php b/phpBB/search.php
index 9176356595..c67581490b 100644
--- a/phpBB/search.php
+++ b/phpBB/search.php
@@ -1047,31 +1047,10 @@ $template->assign_vars(array(
 // only show recent searches to search administrators
 if ($auth->acl_get('a_search'))
 {
-	// Handle large objects differently for Oracle and MSSQL
-	switch ($db->sql_layer)
-	{
-		case 'oracle':
-			$sql = 'SELECT search_time, search_keywords
-				FROM ' . SEARCH_RESULTS_TABLE . '
-				WHERE dbms_lob.getlength(search_keywords) > 0
-				ORDER BY search_time DESC';
-		break;
-	
-		case 'mssql':
-		case 'mssql_odbc':
-			$sql = 'SELECT search_time, search_keywords
-				FROM ' . SEARCH_RESULTS_TABLE . '
-				WHERE DATALENGTH(search_keywords) > 0
-				ORDER BY search_time DESC';
-		break;
-	
-		default:
-			$sql = 'SELECT search_time, search_keywords
-				FROM ' . SEARCH_RESULTS_TABLE . '
-				WHERE search_keywords <> \'\'
-				ORDER BY search_time DESC';
-		break;
-	}
+	$sql = 'SELECT search_time, search_keywords
+		FROM ' . SEARCH_RESULTS_TABLE . '
+		WHERE ' . $db->sql_function('length_text', 'search_keywords') . ' > 0
+		ORDER BY search_time DESC';
 	$result = $db->sql_query_limit($sql, 5);
 
 	while ($row = $db->sql_fetchrow($result))
diff --git a/phpBB/style.php b/phpBB/style.php
index 37e396bb29..7dfd3886ff 100644
--- a/phpBB/style.php
+++ b/phpBB/style.php
@@ -140,7 +140,7 @@ if ($id)
 	}
 
 	// Expire time of seven days if not recached
-	$expire_time = 7*86400;
+	$expire_time = 7 * 86400;
 	$recache = false;
 
 	// Re-cache stylesheet data if necessary
@@ -177,7 +177,10 @@ if ($id)
 
 	if ($recache)
 	{
-		include_once($phpbb_root_path . 'includes/acp/acp_styles.' . $phpEx);
+		if (!class_exists('acp_styles'))
+		{
+			include($phpbb_root_path . 'includes/acp/acp_styles.' . $phpEx);
+		}
 
 		$theme['theme_data'] = acp_styles::db_theme_data($theme);
 		$theme['theme_mtime'] = $update_time;
diff --git a/phpBB/viewforum.php b/phpBB/viewforum.php
index 5a618f4a2c..cb9b125400 100644
--- a/phpBB/viewforum.php
+++ b/phpBB/viewforum.php
@@ -405,28 +405,38 @@ else if (empty($active_forum_ary['exclude_forum_id']))
 else
 {
 	$get_forum_ids = array_diff($active_forum_ary['forum_id'], $active_forum_ary['exclude_forum_id']);
-	$sql_where = (sizeof($get_forum_ids)) ? $db->sql_in_set('t.forum_id', $get_forum_ids) : 't.forum_id = ' . $forum_id;
+	$sql_where = $db->sql_in_set('t.forum_id', $get_forum_ids);
 }
 
+// Grab just the sorted topic ids
+$sql = 'SELECT t.topic_id
+	FROM ' . TOPICS_TABLE . " t
+	WHERE $sql_where
+		AND t.topic_type IN (" . POST_NORMAL . ', ' . POST_STICKY . ")
+		$sql_approved
+		$sql_limit_time
+	ORDER BY t.topic_type " . ((!$store_reverse) ? 'DESC' : 'ASC') . ', ' . $sql_sort_order;
+$result = $db->sql_query_limit($sql, $sql_limit, $sql_start);
+while ($row = $db->sql_fetchrow($result))
+{
+	$topic_list[] = (int) $row['topic_id'];
+}
+$db->sql_freeresult($result);
+
 // SQL array for obtaining topics/stickies
 $sql_array = array(
 	'SELECT'		=> $sql_array['SELECT'],
 	'FROM'			=> $sql_array['FROM'],
 	'LEFT_JOIN'		=> $sql_array['LEFT_JOIN'],
 
-	'WHERE'			=> $sql_where . '
-		AND t.topic_type IN (' . POST_NORMAL . ', ' . POST_STICKY . ")
-		$sql_approved
-		$sql_limit_time",
-
-	'ORDER_BY'		=> 't.topic_type ' . ((!$store_reverse) ? 'DESC' : 'ASC') . ', ' . $sql_sort_order,
+	'WHERE'			=> $db->sql_in_set('t.topic_id', $topic_list),
 );
 
 // If store_reverse, then first obtain topics, then stickies, else the other way around...
 // Funnily enough you typically save one query if going from the last page to the middle (store_reverse) because
 // the number of stickies are not known
 $sql = $db->sql_build_query('SELECT', $sql_array);
-$result = $db->sql_query_limit($sql, $sql_limit, $sql_start);
+$result = $db->sql_query($sql);
 
 $shadow_topic_list = array();
 while ($row = $db->sql_fetchrow($result))
@@ -437,7 +447,6 @@ while ($row = $db->sql_fetchrow($result))
 	}
 
 	$rowset[$row['topic_id']] = $row;
-	$topic_list[] = $row['topic_id'];
 }
 $db->sql_freeresult($result);
 
diff --git a/phpBB/viewonline.php b/phpBB/viewonline.php
index ea29e09660..c27788c4c8 100644
--- a/phpBB/viewonline.php
+++ b/phpBB/viewonline.php
@@ -97,23 +97,21 @@ $guest_counter = 0;
 // Get number of online guests (if we do not display them)
 if (!$show_guests)
 {
-	switch ($db->sql_layer)
+	if ($db->count_distinct)
 	{
-		case 'sqlite':
-			$sql = 'SELECT COUNT(session_ip) as num_guests
-				FROM (
-					SELECT DISTINCT session_ip
-						FROM ' . SESSIONS_TABLE . '
-						WHERE session_user_id = ' . ANONYMOUS . '
-							AND session_time >= ' . (time() - ($config['load_online_time'] * 60)) .
-				')';
-		break;
-
-		default:
-			$sql = 'SELECT COUNT(DISTINCT session_ip) as num_guests
+		$sql = 'SELECT COUNT(DISTINCT session_ip) as num_guests
 				FROM ' . SESSIONS_TABLE . '
 				WHERE session_user_id = ' . ANONYMOUS . '
 					AND session_time >= ' . (time() - ($config['load_online_time'] * 60));
+	else
+	{
+		$sql = 'SELECT COUNT(session_ip) as num_guests
+			FROM (
+				SELECT DISTINCT session_ip
+					FROM ' . SESSIONS_TABLE . '
+					WHERE session_user_id = ' . ANONYMOUS . '
+						AND session_time >= ' . (time() - ($config['load_online_time'] * 60)) .
+			')';
 		break;
 	}
 	$result = $db->sql_query($sql);