10 files changed, 381 insertions, 606 deletions
diff --git a/phpBB/phpbb/db/driver/driver.php b/phpBB/phpbb/db/driver/driver.php
index 01dd66cd6e..214c5590e7 100644
--- a/phpBB/phpbb/db/driver/driver.php
+++ b/phpBB/phpbb/db/driver/driver.php
@@ -66,6 +66,15 @@ abstract class driver implements driver_interface
 	*/
 	var $sql_server_version = false;
 
+	const LOGICAL_OP = 0;
+	const STATEMENTS = 1;
+	const LEFT_STMT = 0;
+	const COMPARE_OP = 1;
+	const RIGHT_STMT = 2;
+	const SUBQUERY_OP = 3;
+	const SUBQUERY_SELECT_TYPE = 4;
+	const SUBQUERY_BUILD = 5;
+
 	/**
 	* Constructor
 	*/
@@ -271,7 +280,7 @@ abstract class driver implements driver_interface
 			$query_id = $this->query_result;
 		}
 
-		if ($query_id !== false)
+		if ($query_id)
 		{
 			$result = array();
 			while ($row = $this->sql_fetchrow($query_id))
@@ -302,7 +311,7 @@ abstract class driver implements driver_interface
 			return $cache->sql_rowseek($rownum, $query_id);
 		}
 
-		if ($query_id === false)
+		if (!$query_id)
 		{
 			return false;
 		}
@@ -310,7 +319,7 @@ abstract class driver implements driver_interface
 		$this->sql_freeresult($query_id);
 		$query_id = $this->sql_query($this->last_query_text);
 
-		if ($query_id === false)
+		if (!$query_id)
 		{
 			return false;
 		}
@@ -339,7 +348,7 @@ abstract class driver implements driver_interface
 			$query_id = $this->query_result;
 		}
 
-		if ($query_id !== false)
+		if ($query_id)
 		{
 			if ($rownum !== false)
 			{
@@ -363,8 +372,8 @@ abstract class driver implements driver_interface
 	*/
 	function sql_like_expression($expression)
 	{
-		$expression = utf8_str_replace(array('_', '%'), array("\_", "\%"), $expression);
-		$expression = utf8_str_replace(array(chr(0) . "\_", chr(0) . "\%"), array('_', '%'), $expression);
+		$expression = str_replace(array('_', '%'), array("\_", "\%"), $expression);
+		$expression = str_replace(array(chr(0) . "\_", chr(0) . "\%"), array('_', '%'), $expression);
 
 		return $this->_sql_like_expression('LIKE \'' . $this->sql_escape($expression) . '\'');
 	}
@@ -374,8 +383,8 @@ abstract class driver implements driver_interface
 	*/
 	function sql_not_like_expression($expression)
 	{
-		$expression = utf8_str_replace(array('_', '%'), array("\_", "\%"), $expression);
-		$expression = utf8_str_replace(array(chr(0) . "\_", chr(0) . "\%"), array('_', '%'), $expression);
+		$expression = str_replace(array('_', '%'), array("\_", "\%"), $expression);
+		$expression = str_replace(array(chr(0) . "\_", chr(0) . "\%"), array('_', '%'), $expression);
 
 		return $this->_sql_not_like_expression('NOT LIKE \'' . $this->sql_escape($expression) . '\'');
 	}
@@ -774,7 +783,18 @@ abstract class driver implements driver_interface
 
 				if (!empty($array['WHERE']))
 				{
-					$sql .= ' WHERE ' . $this->_sql_custom_build('WHERE', $array['WHERE']);
+					$sql .= ' WHERE ';
+
+					if (is_array($array['WHERE']))
+					{
+						$sql_where = $this->_process_boolean_tree_first($array['WHERE']);
+					}
+					else
+					{
+						$sql_where = $array['WHERE'];
+					}
+
+					$sql .= $this->_sql_custom_build('WHERE', $sql_where);
 				}
 
 				if (!empty($array['GROUP_BY']))
@@ -793,6 +813,130 @@ abstract class driver implements driver_interface
 		return $sql;
 	}
 
+
+	protected function _process_boolean_tree_first($operations_ary)
+	{
+		// In cases where an array exists but there is no head condition,
+		// it should be because there's only 1 WHERE clause. This seems the best way to deal with it.
+		if ($operations_ary[self::LOGICAL_OP] !== 'AND' &&
+			$operations_ary[self::LOGICAL_OP] !== 'OR')
+		{
+			$operations_ary = array('AND', array($operations_ary));
+		}
+		return $this->_process_boolean_tree($operations_ary) . "\n";
+	}
+
+	protected function _process_boolean_tree($operations_ary)
+	{
+		$operation = $operations_ary[self::LOGICAL_OP];
+
+		foreach ($operations_ary[self::STATEMENTS] as &$condition)
+		{
+			switch ($condition[self::LOGICAL_OP])
+			{
+				case 'AND':
+				case 'OR':
+
+					$condition = ' ( ' . $this->_process_boolean_tree($condition) . ') ';
+
+				break;
+				case 'NOT':
+
+					$condition = ' NOT (' . $this->_process_boolean_tree($condition) . ') ';
+
+				break;
+
+				default:
+
+					switch (sizeof($condition))
+					{
+						case 3:
+
+							// Typical 3 element clause with {left hand} {operator} {right hand}
+							switch ($condition[self::COMPARE_OP])
+							{
+								case 'IN':
+								case 'NOT_IN':
+
+									// As this is used with an IN, assume it is a set of elements for sql_in_set()
+									$condition = $this->sql_in_set($condition[self::LEFT_STMT], $condition[self::RIGHT_STMT], $condition[self::COMPARE_OP] === 'NOT_IN', true);
+
+								break;
+
+								case 'LIKE':
+
+									$condition = $condition[self::LEFT_STMT] . ' ' . $this->sql_like_expression($condition[self::RIGHT_STMT]) . ' ';
+
+								break;
+
+								case 'NOT_LIKE':
+
+									$condition = $condition[self::LEFT_STMT] . ' ' . $this->sql_not_like_expression($condition[self::RIGHT_STMT]) . ' ';
+
+								break;
+
+								case 'IS_NOT':
+
+									$condition[self::COMPARE_OP] = 'IS NOT';
+
+								// no break
+								case 'IS':
+
+									// If the value is NULL, the string of it is the empty string ('') which is not the intended result.
+									// this should solve that
+									if ($condition[self::RIGHT_STMT] === null)
+									{
+										$condition[self::RIGHT_STMT] = 'NULL';
+									}
+
+									$condition = implode(' ', $condition);
+
+								break;
+
+								default:
+
+									$condition = implode(' ', $condition);
+
+								break;
+							}
+
+						break;
+
+						case 5:
+
+							// Subquery with {left hand} {operator} {compare kind} {SELECT Kind } {Sub Query}
+
+							$condition = $condition[self::LEFT_STMT] . ' ' . $condition[self::COMPARE_OP] . ' ' . $condition[self::SUBQUERY_OP] . ' ( ';
+							$condition .= $this->sql_build_query($condition[self::SUBQUERY_SELECT_TYPE], $condition[self::SUBQUERY_BUILD]);
+							$condition .= ' )';
+
+						break;
+
+						default:
+							// This is an unpredicted clause setup. Just join all elements.
+							$condition = implode(' ', $condition);
+
+						break;
+					}
+
+				break;
+			}
+
+		}
+
+		if ($operation === 'NOT')
+		{
+			$operations_ary =  implode("", $operations_ary[self::STATEMENTS]);
+		}
+		else
+		{
+			$operations_ary = implode(" \n	$operation ", $operations_ary[self::STATEMENTS]);
+		}
+
+		return $operations_ary;
+	}
+
+
 	/**
 	* {@inheritDoc}
 	*/
@@ -868,7 +1012,7 @@ abstract class driver implements driver_interface
 	*/
 	function sql_report($mode, $query = '')
 	{
-		global $cache, $starttime, $phpbb_root_path, $phpbb_path_helper, $user;
+		global $cache, $starttime, $phpbb_root_path, $phpbb_path_helper;
 		global $request;
 
 		if (is_object($request) && !$request->variable('explain', false))
diff --git a/phpBB/phpbb/db/driver/mssql.php b/phpBB/phpbb/db/driver/mssql.php
deleted file mode 100644
index f9ea884ce2..0000000000
--- a/phpBB/phpbb/db/driver/mssql.php
+++ /dev/null
@@ -1,476 +0,0 @@
-<?php
-/**
-*
-* This file is part of the phpBB Forum Software package.
-*
-* @copyright (c) phpBB Limited <https://www.phpbb.com>
-* @license GNU General Public License, version 2 (GPL-2.0)
-*
-* For full copyright and license information, please see
-* the docs/CREDITS.txt file.
-*
-*/
-
-namespace phpbb\db\driver;
-
-/**
-* MSSQL Database Abstraction Layer
-* Minimum Requirement is MSSQL 2000+
-*/
-class mssql extends \phpbb\db\driver\driver
-{
-	var $connect_error = '';
-
-	/**
-	* {@inheritDoc}
-	*/
-	function sql_connect($sqlserver, $sqluser, $sqlpassword, $database, $port = false, $persistency = false, $new_link = false)
-	{
-		if (!function_exists('mssql_connect'))
-		{
-			$this->connect_error = 'mssql_connect function does not exist, is mssql extension installed?';
-			return $this->sql_error('');
-		}
-
-		$this->persistency = $persistency;
-		$this->user = $sqluser;
-		$this->dbname = $database;
-
-		$port_delimiter = (defined('PHP_OS') && substr(PHP_OS, 0, 3) === 'WIN') ? ',' : ':';
-		$this->server = $sqlserver . (($port) ? $port_delimiter . $port : '');
-
-		@ini_set('mssql.charset', 'UTF-8');
-		@ini_set('mssql.textlimit', 2147483647);
-		@ini_set('mssql.textsize', 2147483647);
-
-		$this->db_connect_id = ($this->persistency) ? @mssql_pconnect($this->server, $this->user, $sqlpassword, $new_link) : @mssql_connect($this->server, $this->user, $sqlpassword, $new_link);
-
-		if ($this->db_connect_id && $this->dbname != '')
-		{
-			if (!@mssql_select_db($this->dbname, $this->db_connect_id))
-			{
-				@mssql_close($this->db_connect_id);
-				return false;
-			}
-		}
-
-		return ($this->db_connect_id) ? $this->db_connect_id : $this->sql_error('');
-	}
-
-	/**
-	* {@inheritDoc}
-	*/
-	function sql_server_info($raw = false, $use_cache = true)
-	{
-		global $cache;
-
-		if (!$use_cache || empty($cache) || ($this->sql_server_version = $cache->get('mssql_version')) === false)
-		{
-			$result_id = @mssql_query("SELECT SERVERPROPERTY('productversion'), SERVERPROPERTY('productlevel'), SERVERPROPERTY('edition')", $this->db_connect_id);
-
-			$row = false;
-			if ($result_id)
-			{
-				$row = @mssql_fetch_assoc($result_id);
-				@mssql_free_result($result_id);
-			}
-
-			$this->sql_server_version = ($row) ? trim(implode(' ', $row)) : 0;
-
-			if (!empty($cache) && $use_cache)
-			{
-				$cache->put('mssql_version', $this->sql_server_version);
-			}
-		}
-
-		if ($raw)
-		{
-			return $this->sql_server_version;
-		}
-
-		return ($this->sql_server_version) ? 'MSSQL<br />' . $this->sql_server_version : 'MSSQL';
-	}
-
-	/**
-	* {@inheritDoc}
-	*/
-	public function sql_concatenate($expr1, $expr2)
-	{
-		return $expr1 . ' + ' . $expr2;
-	}
-
-	/**
-	* SQL Transaction
-	* @access private
-	*/
-	function _sql_transaction($status = 'begin')
-	{
-		switch ($status)
-		{
-			case 'begin':
-				return @mssql_query('BEGIN TRANSACTION', $this->db_connect_id);
-			break;
-
-			case 'commit':
-				return @mssql_query('COMMIT TRANSACTION', $this->db_connect_id);
-			break;
-
-			case 'rollback':
-				return @mssql_query('ROLLBACK TRANSACTION', $this->db_connect_id);
-			break;
-		}
-
-		return true;
-	}
-
-	/**
-	* {@inheritDoc}
-	*/
-	function sql_query($query = '', $cache_ttl = 0)
-	{
-		if ($query != '')
-		{
-			global $cache;
-
-			// EXPLAIN only in extra debug mode
-			if (defined('DEBUG'))
-			{
-				$this->sql_report('start', $query);
-			}
-			else if (defined('PHPBB_DISPLAY_LOAD_TIME'))
-			{
-				$this->curtime = microtime(true);
-			}
-
-			$this->query_result = ($cache && $cache_ttl) ? $cache->sql_load($query) : false;
-			$this->sql_add_num_queries($this->query_result);
-
-			if ($this->query_result === false)
-			{
-				if (($this->query_result = @mssql_query($query, $this->db_connect_id)) === false)
-				{
-					$this->sql_error($query);
-				}
-
-				if (defined('DEBUG'))
-				{
-					$this->sql_report('stop', $query);
-				}
-				else if (defined('PHPBB_DISPLAY_LOAD_TIME'))
-				{
-					$this->sql_time += microtime(true) - $this->curtime;
-				}
-
-				if ($cache && $cache_ttl)
-				{
-					$this->open_queries[(int) $this->query_result] = $this->query_result;
-					$this->query_result = $cache->sql_save($this, $query, $this->query_result, $cache_ttl);
-				}
-				else if (strpos($query, 'SELECT') === 0 && $this->query_result)
-				{
-					$this->open_queries[(int) $this->query_result] = $this->query_result;
-				}
-			}
-			else if (defined('DEBUG'))
-			{
-				$this->sql_report('fromcache', $query);
-			}
-		}
-		else
-		{
-			return false;
-		}
-
-		return $this->query_result;
-	}
-
-	/**
-	* Build LIMIT query
-	*/
-	function _sql_query_limit($query, $total, $offset = 0, $cache_ttl = 0)
-	{
-		$this->query_result = false;
-
-		// Since TOP is only returning a set number of rows we won't need it if total is set to 0 (return all rows)
-		if ($total)
-		{
-			// We need to grab the total number of rows + the offset number of rows to get the correct result
-			if (strpos($query, 'SELECT DISTINCT') === 0)
-			{
-				$query = 'SELECT DISTINCT TOP ' . ($total + $offset) . ' ' . substr($query, 15);
-			}
-			else
-			{
-				$query = 'SELECT TOP ' . ($total + $offset) . ' ' . substr($query, 6);
-			}
-		}
-
-		$result = $this->sql_query($query, $cache_ttl);
-
-		// Seek by $offset rows
-		if ($offset)
-		{
-			$this->sql_rowseek($offset, $result);
-		}
-
-		return $result;
-	}
-
-	/**
-	* {@inheritDoc}
-	*/
-	function sql_affectedrows()
-	{
-		return ($this->db_connect_id) ? @mssql_rows_affected($this->db_connect_id) : false;
-	}
-
-	/**
-	* {@inheritDoc}
-	*/
-	function sql_fetchrow($query_id = false)
-	{
-		global $cache;
-
-		if ($query_id === false)
-		{
-			$query_id = $this->query_result;
-		}
-
-		if ($cache && $cache->sql_exists($query_id))
-		{
-			return $cache->sql_fetchrow($query_id);
-		}
-
-		if ($query_id === false)
-		{
-			return false;
-		}
-
-		$row = @mssql_fetch_assoc($query_id);
-
-		// I hope i am able to remove this later... hopefully only a PHP or MSSQL bug
-		if ($row)
-		{
-			foreach ($row as $key => $value)
-			{
-				$row[$key] = ($value === ' ' || $value === null) ? '' : $value;
-			}
-		}
-
-		return $row;
-	}
-
-	/**
-	* {@inheritDoc}
-	*/
-	function sql_rowseek($rownum, &$query_id)
-	{
-		global $cache;
-
-		if ($query_id === false)
-		{
-			$query_id = $this->query_result;
-		}
-
-		if ($cache && $cache->sql_exists($query_id))
-		{
-			return $cache->sql_rowseek($rownum, $query_id);
-		}
-
-		return ($query_id !== false) ? @mssql_data_seek($query_id, $rownum) : false;
-	}
-
-	/**
-	* {@inheritDoc}
-	*/
-	function sql_nextid()
-	{
-		$result_id = @mssql_query('SELECT SCOPE_IDENTITY()', $this->db_connect_id);
-		if ($result_id)
-		{
-			if ($row = @mssql_fetch_assoc($result_id))
-			{
-				@mssql_free_result($result_id);
-				return $row['computed'];
-			}
-			@mssql_free_result($result_id);
-		}
-
-		return false;
-	}
-
-	/**
-	* {@inheritDoc}
-	*/
-	function sql_freeresult($query_id = false)
-	{
-		global $cache;
-
-		if ($query_id === false)
-		{
-			$query_id = $this->query_result;
-		}
-
-		if ($cache && !is_object($query_id) && $cache->sql_exists($query_id))
-		{
-			return $cache->sql_freeresult($query_id);
-		}
-
-		if (isset($this->open_queries[(int) $query_id]))
-		{
-			unset($this->open_queries[(int) $query_id]);
-			return @mssql_free_result($query_id);
-		}
-
-		return false;
-	}
-
-	/**
-	* {@inheritDoc}
-	*/
-	function sql_escape($msg)
-	{
-		return str_replace(array("'", "\0"), array("''", ''), $msg);
-	}
-
-	/**
-	* {@inheritDoc}
-	*/
-	function sql_lower_text($column_name)
-	{
-		return "LOWER(SUBSTRING($column_name, 1, DATALENGTH($column_name)))";
-	}
-
-	/**
-	* Build LIKE expression
-	* @access private
-	*/
-	function _sql_like_expression($expression)
-	{
-		return $expression . " ESCAPE '\\'";
-	}
-
-	/**
-	* Build NOT LIKE expression
-	* @access private
-	*/
-	function _sql_not_like_expression($expression)
-	{
-		return $expression . " ESCAPE '\\'";
-	}
-
-	/**
-	* return sql error array
-	* @access private
-	*/
-	function _sql_error()
-	{
-		if (function_exists('mssql_get_last_message'))
-		{
-			$error = array(
-				'message'	=> @mssql_get_last_message(),
-				'code'		=> '',
-			);
-
-			// Get error code number
-			$result_id = @mssql_query('SELECT @@ERROR as code', $this->db_connect_id);
-			if ($result_id)
-			{
-				$row = @mssql_fetch_assoc($result_id);
-				$error['code'] = $row['code'];
-				@mssql_free_result($result_id);
-			}
-
-			// Get full error message if possible
-			$sql = 'SELECT CAST(description as varchar(255)) as message
-				FROM master.dbo.sysmessages
-				WHERE error = ' . $error['code'];
-			$result_id = @mssql_query($sql);
-
-			if ($result_id)
-			{
-				$row = @mssql_fetch_assoc($result_id);
-				if (!empty($row['message']))
-				{
-					$error['message'] .= '<br />' . $row['message'];
-				}
-				@mssql_free_result($result_id);
-			}
-		}
-		else
-		{
-			$error = array(
-				'message'	=> $this->connect_error,
-				'code'		=> '',
-			);
-		}
-
-		return $error;
-	}
-
-	/**
-	* Build db-specific query data
-	* @access private
-	*/
-	function _sql_custom_build($stage, $data)
-	{
-		return $data;
-	}
-
-	/**
-	* Close sql connection
-	* @access private
-	*/
-	function _sql_close()
-	{
-		return @mssql_close($this->db_connect_id);
-	}
-
-	/**
-	* Build db-specific report
-	* @access private
-	*/
-	function _sql_report($mode, $query = '')
-	{
-		switch ($mode)
-		{
-			case 'start':
-				$html_table = false;
-				@mssql_query('SET SHOWPLAN_TEXT ON;', $this->db_connect_id);
-				if ($result = @mssql_query($query, $this->db_connect_id))
-				{
-					@mssql_next_result($result);
-					while ($row = @mssql_fetch_row($result))
-					{
-						$html_table = $this->sql_report('add_select_row', $query, $html_table, $row);
-					}
-				}
-				@mssql_query('SET SHOWPLAN_TEXT OFF;', $this->db_connect_id);
-				@mssql_free_result($result);
-
-				if ($html_table)
-				{
-					$this->html_hold .= '</table>';
-				}
-			break;
-
-			case 'fromcache':
-				$endtime = explode(' ', microtime());
-				$endtime = $endtime[0] + $endtime[1];
-
-				$result = @mssql_query($query, $this->db_connect_id);
-				while ($void = @mssql_fetch_assoc($result))
-				{
-					// Take the time spent on parsing rows into account
-				}
-				@mssql_free_result($result);
-
-				$splittime = explode(' ', microtime());
-				$splittime = $splittime[0] + $splittime[1];
-
-				$this->sql_report('record_fromcache', $query, $endtime, $splittime);
-
-			break;
-		}
-	}
-}
diff --git a/phpBB/phpbb/db/driver/mssql_odbc.php b/phpBB/phpbb/db/driver/mssql_odbc.php
index 8e5d4c7a4c..9d9ad603e0 100644
--- a/phpBB/phpbb/db/driver/mssql_odbc.php
+++ b/phpBB/phpbb/db/driver/mssql_odbc.php
@@ -98,8 +98,8 @@ class mssql_odbc extends \phpbb\db\driver\mssql_base
 			$row = false;
 			if ($result_id)
 			{
-				$row = @odbc_fetch_array($result_id);
-				@odbc_free_result($result_id);
+				$row = odbc_fetch_array($result_id);
+				odbc_free_result($result_id);
 			}
 
 			$this->sql_server_version = ($row) ? trim(implode(' ', $row)) : 0;
@@ -181,12 +181,17 @@ class mssql_odbc extends \phpbb\db\driver\mssql_base
 					$this->sql_time += microtime(true) - $this->curtime;
 				}
 
+				if (!$this->query_result)
+				{
+					return false;
+				}
+
 				if ($cache && $cache_ttl)
 				{
 					$this->open_queries[(int) $this->query_result] = $this->query_result;
 					$this->query_result = $cache->sql_save($this, $query, $this->query_result, $cache_ttl);
 				}
-				else if (strpos($query, 'SELECT') === 0 && $this->query_result)
+				else if (strpos($query, 'SELECT') === 0)
 				{
 					$this->open_queries[(int) $this->query_result] = $this->query_result;
 				}
@@ -261,7 +266,7 @@ class mssql_odbc extends \phpbb\db\driver\mssql_base
 			return $cache->sql_fetchrow($query_id);
 		}
 
-		return ($query_id !== false) ? @odbc_fetch_array($query_id) : false;
+		return ($query_id) ? odbc_fetch_array($query_id) : false;
 	}
 
 	/**
@@ -273,13 +278,13 @@ class mssql_odbc extends \phpbb\db\driver\mssql_base
 
 		if ($result_id)
 		{
-			if (@odbc_fetch_array($result_id))
+			if (odbc_fetch_array($result_id))
 			{
-				$id = @odbc_result($result_id, 1);
-				@odbc_free_result($result_id);
+				$id = odbc_result($result_id, 1);
+				odbc_free_result($result_id);
 				return $id;
 			}
-			@odbc_free_result($result_id);
+			odbc_free_result($result_id);
 		}
 
 		return false;
@@ -305,7 +310,7 @@ class mssql_odbc extends \phpbb\db\driver\mssql_base
 		if (isset($this->open_queries[(int) $query_id]))
 		{
 			unset($this->open_queries[(int) $query_id]);
-			return @odbc_free_result($query_id);
+			return odbc_free_result($query_id);
 		}
 
 		return false;
@@ -360,11 +365,14 @@ class mssql_odbc extends \phpbb\db\driver\mssql_base
 				$endtime = $endtime[0] + $endtime[1];
 
 				$result = @odbc_exec($this->db_connect_id, $query);
-				while ($void = @odbc_fetch_array($result))
+				if ($result)
 				{
-					// Take the time spent on parsing rows into account
+					while ($void = odbc_fetch_array($result))
+					{
+						// Take the time spent on parsing rows into account
+					}
+					odbc_free_result($result);
 				}
-				@odbc_free_result($result);
 
 				$splittime = explode(' ', microtime());
 				$splittime = $splittime[0] + $splittime[1];
diff --git a/phpBB/phpbb/db/driver/mssqlnative.php b/phpBB/phpbb/db/driver/mssqlnative.php
index 46a9b3a477..50dce35baa 100644
--- a/phpBB/phpbb/db/driver/mssqlnative.php
+++ b/phpBB/phpbb/db/driver/mssqlnative.php
@@ -154,12 +154,17 @@ class mssqlnative extends \phpbb\db\driver\mssql_base
 					$this->sql_time += microtime(true) - $this->curtime;
 				}
 
+				if (!$this->query_result)
+				{
+					return false;
+				}
+
 				if ($cache && $cache_ttl)
 				{
 					$this->open_queries[(int) $this->query_result] = $this->query_result;
 					$this->query_result = $cache->sql_save($this, $query, $this->query_result, $cache_ttl);
 				}
-				else if (strpos($query, 'SELECT') === 0 && $this->query_result)
+				else if (strpos($query, 'SELECT') === 0)
 				{
 					$this->open_queries[(int) $this->query_result] = $this->query_result;
 				}
@@ -242,12 +247,12 @@ class mssqlnative extends \phpbb\db\driver\mssql_base
 			return $cache->sql_fetchrow($query_id);
 		}
 
-		if ($query_id === false)
+		if (!$query_id)
 		{
 			return false;
 		}
 
-		$row = @sqlsrv_fetch_array($query_id, SQLSRV_FETCH_ASSOC);
+		$row = sqlsrv_fetch_array($query_id, SQLSRV_FETCH_ASSOC);
 
 		if ($row)
 		{
@@ -272,11 +277,11 @@ class mssqlnative extends \phpbb\db\driver\mssql_base
 	{
 		$result_id = @sqlsrv_query($this->db_connect_id, 'SELECT @@IDENTITY');
 
-		if ($result_id !== false)
+		if ($result_id)
 		{
-			$row = @sqlsrv_fetch_array($result_id);
+			$row = sqlsrv_fetch_array($result_id);
 			$id = $row[0];
-			@sqlsrv_free_stmt($result_id);
+			sqlsrv_free_stmt($result_id);
 			return $id;
 		}
 		else
@@ -305,7 +310,7 @@ class mssqlnative extends \phpbb\db\driver\mssql_base
 		if (isset($this->open_queries[(int) $query_id]))
 		{
 			unset($this->open_queries[(int) $query_id]);
-			return @sqlsrv_free_stmt($query_id);
+			return sqlsrv_free_stmt($query_id);
 		}
 
 		return false;
@@ -378,14 +383,14 @@ class mssqlnative extends \phpbb\db\driver\mssql_base
 				@sqlsrv_query($this->db_connect_id, 'SET SHOWPLAN_TEXT ON;');
 				if ($result = @sqlsrv_query($this->db_connect_id, $query))
 				{
-					@sqlsrv_next_result($result);
-					while ($row = @sqlsrv_fetch_array($result))
+					sqlsrv_next_result($result);
+					while ($row = sqlsrv_fetch_array($result))
 					{
 						$html_table = $this->sql_report('add_select_row', $query, $html_table, $row);
 					}
+					sqlsrv_free_stmt($result);
 				}
 				@sqlsrv_query($this->db_connect_id, 'SET SHOWPLAN_TEXT OFF;');
-				@sqlsrv_free_stmt($result);
 
 				if ($html_table)
 				{
@@ -398,11 +403,14 @@ class mssqlnative extends \phpbb\db\driver\mssql_base
 				$endtime = $endtime[0] + $endtime[1];
 
 				$result = @sqlsrv_query($this->db_connect_id, $query);
-				while ($void = @sqlsrv_fetch_array($result))
+				if ($result)
 				{
-					// Take the time spent on parsing rows into account
+					while ($void = sqlsrv_fetch_array($result))
+					{
+						// Take the time spent on parsing rows into account
+					}
+					sqlsrv_free_stmt($result);
 				}
-				@sqlsrv_free_stmt($result);
 
 				$splittime = explode(' ', microtime());
 				$splittime = $splittime[0] + $splittime[1];
diff --git a/phpBB/phpbb/db/driver/mysql.php b/phpBB/phpbb/db/driver/mysql.php
index e93c7239e8..a94e88b331 100644
--- a/phpBB/phpbb/db/driver/mysql.php
+++ b/phpBB/phpbb/db/driver/mysql.php
@@ -70,9 +70,16 @@ class mysql extends \phpbb\db\driver\mysql_base
 					if (version_compare($this->sql_server_info(true), '5.0.2', '>='))
 					{
 						$result = @mysql_query('SELECT @@session.sql_mode AS sql_mode', $this->db_connect_id);
-						$row = @mysql_fetch_assoc($result);
-						@mysql_free_result($result);
-						$modes = array_map('trim', explode(',', $row['sql_mode']));
+						if ($result)
+						{
+							$row = mysql_fetch_assoc($result);
+							mysql_free_result($result);
+							$modes = array_map('trim', explode(',', $row['sql_mode']));
+						}
+						else
+						{
+							$modes = array();
+						}
 
 						// TRADITIONAL includes STRICT_ALL_TABLES and STRICT_TRANS_TABLES
 						if (!in_array('TRADITIONAL', $modes))
@@ -114,14 +121,17 @@ class mysql extends \phpbb\db\driver\mysql_base
 		if (!$use_cache || empty($cache) || ($this->sql_server_version = $cache->get('mysql_version')) === false)
 		{
 			$result = @mysql_query('SELECT VERSION() AS version', $this->db_connect_id);
-			$row = @mysql_fetch_assoc($result);
-			@mysql_free_result($result);
+			if ($result)
+			{
+				$row = mysql_fetch_assoc($result);
+				mysql_free_result($result);
 
-			$this->sql_server_version = $row['version'];
+				$this->sql_server_version = $row['version'];
 
-			if (!empty($cache) && $use_cache)
-			{
-				$cache->put('mysql_version', $this->sql_server_version);
+				if (!empty($cache) && $use_cache)
+				{
+					$cache->put('mysql_version', $this->sql_server_version);
+				}
 			}
 		}
 
@@ -190,12 +200,17 @@ class mysql extends \phpbb\db\driver\mysql_base
 					$this->sql_time += microtime(true) - $this->curtime;
 				}
 
+				if (!$this->query_result)
+				{
+					return false;
+				}
+
 				if ($cache && $cache_ttl)
 				{
 					$this->open_queries[(int) $this->query_result] = $this->query_result;
 					$this->query_result = $cache->sql_save($this, $query, $this->query_result, $cache_ttl);
 				}
-				else if (strpos($query, 'SELECT') === 0 && $this->query_result)
+				else if (strpos($query, 'SELECT') === 0)
 				{
 					$this->open_queries[(int) $this->query_result] = $this->query_result;
 				}
@@ -257,7 +272,7 @@ class mysql extends \phpbb\db\driver\mysql_base
 			return $cache->sql_fetchrow($query_id);
 		}
 
-		return ($query_id !== false) ? @mysql_fetch_assoc($query_id) : false;
+		return ($query_id) ? mysql_fetch_assoc($query_id) : false;
 	}
 
 	/**
@@ -308,7 +323,7 @@ class mysql extends \phpbb\db\driver\mysql_base
 		if (isset($this->open_queries[(int) $query_id]))
 		{
 			unset($this->open_queries[(int) $query_id]);
-			return @mysql_free_result($query_id);
+			return mysql_free_result($query_id);
 		}
 
 		return false;
@@ -411,12 +426,12 @@ class mysql extends \phpbb\db\driver\mysql_base
 
 					if ($result = @mysql_query("EXPLAIN $explain_query", $this->db_connect_id))
 					{
-						while ($row = @mysql_fetch_assoc($result))
+						while ($row = mysql_fetch_assoc($result))
 						{
 							$html_table = $this->sql_report('add_select_row', $query, $html_table, $row);
 						}
+						mysql_free_result($result);
 					}
-					@mysql_free_result($result);
 
 					if ($html_table)
 					{
@@ -431,7 +446,7 @@ class mysql extends \phpbb\db\driver\mysql_base
 						if ($result = @mysql_query('SHOW PROFILE ALL;', $this->db_connect_id))
 						{
 							$this->html_hold .= '<br />';
-							while ($row = @mysql_fetch_assoc($result))
+							while ($row = mysql_fetch_assoc($result))
 							{
 								// make <unknown> HTML safe
 								if (!empty($row['Source_function']))
@@ -449,8 +464,8 @@ class mysql extends \phpbb\db\driver\mysql_base
 								}
 								$html_table = $this->sql_report('add_select_row', $query, $html_table, $row);
 							}
+							mysql_free_result($result);
 						}
-						@mysql_free_result($result);
 
 						if ($html_table)
 						{
@@ -468,11 +483,14 @@ class mysql extends \phpbb\db\driver\mysql_base
 				$endtime = $endtime[0] + $endtime[1];
 
 				$result = @mysql_query($query, $this->db_connect_id);
-				while ($void = @mysql_fetch_assoc($result))
+				if ($result)
 				{
-					// Take the time spent on parsing rows into account
+					while ($void = mysql_fetch_assoc($result))
+					{
+						// Take the time spent on parsing rows into account
+					}
+					mysql_free_result($result);
 				}
-				@mysql_free_result($result);
 
 				$splittime = explode(' ', microtime());
 				$splittime = $splittime[0] + $splittime[1];
diff --git a/phpBB/phpbb/db/driver/mysqli.php b/phpBB/phpbb/db/driver/mysqli.php
index c0ddfbf76c..d43e201526 100644
--- a/phpBB/phpbb/db/driver/mysqli.php
+++ b/phpBB/phpbb/db/driver/mysqli.php
@@ -74,9 +74,10 @@ class mysqli extends \phpbb\db\driver\mysql_base
 			if (version_compare($this->sql_server_info(true), '5.0.2', '>='))
 			{
 				$result = @mysqli_query($this->db_connect_id, 'SELECT @@session.sql_mode AS sql_mode');
-				if ($result !== null)
+				if ($result)
 				{
-					$row = @mysqli_fetch_assoc($result);
+					$row = mysqli_fetch_assoc($result);
+					mysqli_free_result($result);
 
 					$modes = array_map('trim', explode(',', $row['sql_mode']));
 				}
@@ -84,7 +85,6 @@ class mysqli extends \phpbb\db\driver\mysql_base
 				{
 					$modes = array();
 				}
-				@mysqli_free_result($result);
 
 				// TRADITIONAL includes STRICT_ALL_TABLES and STRICT_TRANS_TABLES
 				if (!in_array('TRADITIONAL', $modes))
@@ -119,9 +119,10 @@ class mysqli extends \phpbb\db\driver\mysql_base
 		if (!$use_cache || empty($cache) || ($this->sql_server_version = $cache->get('mysqli_version')) === false)
 		{
 			$result = @mysqli_query($this->db_connect_id, 'SELECT VERSION() AS version');
-			if ($result !== null)
+			if ($result)
 			{
-				$row = @mysqli_fetch_assoc($result);
+				$row = mysqli_fetch_assoc($result);
+				mysqli_free_result($result);
 
 				$this->sql_server_version = $row['version'];
 
@@ -130,7 +131,6 @@ class mysqli extends \phpbb\db\driver\mysql_base
 					$cache->put('mysqli_version', $this->sql_server_version);
 				}
 			}
-			@mysqli_free_result($result);
 		}
 
 		return ($raw) ? $this->sql_server_version : 'MySQL(i) ' . $this->sql_server_version;
@@ -202,6 +202,11 @@ class mysqli extends \phpbb\db\driver\mysql_base
 					$this->sql_time += microtime(true) - $this->curtime;
 				}
 
+				if (!$this->query_result)
+				{
+					return false;
+				}
+
 				if ($cache && $cache_ttl)
 				{
 					$this->query_result = $cache->sql_save($this, $query, $this->query_result, $cache_ttl);
@@ -245,9 +250,9 @@ class mysqli extends \phpbb\db\driver\mysql_base
 			return $cache->sql_fetchrow($query_id);
 		}
 
-		if ($query_id !== false && $query_id !== null)
+		if ($query_id)
 		{
-			$result = @mysqli_fetch_assoc($query_id);
+			$result = mysqli_fetch_assoc($query_id);
 			return $result !== null ? $result : false;
 		}
 
@@ -271,7 +276,7 @@ class mysqli extends \phpbb\db\driver\mysql_base
 			return $cache->sql_rowseek($rownum, $query_id);
 		}
 
-		return ($query_id !== false) ? @mysqli_data_seek($query_id, $rownum) : false;
+		return ($query_id) ? @mysqli_data_seek($query_id, $rownum) : false;
 	}
 
 	/**
@@ -299,7 +304,17 @@ class mysqli extends \phpbb\db\driver\mysql_base
 			return $cache->sql_freeresult($query_id);
 		}
 
-		return @mysqli_free_result($query_id);
+		if (!$query_id)
+		{
+			return false;
+		}
+
+		if ($query_id === true)
+		{
+			return true;
+		}
+
+		return mysqli_free_result($query_id);
 	}
 
 	/**
@@ -398,12 +413,12 @@ class mysqli extends \phpbb\db\driver\mysql_base
 
 					if ($result = @mysqli_query($this->db_connect_id, "EXPLAIN $explain_query"))
 					{
-						while ($row = @mysqli_fetch_assoc($result))
+						while ($row = mysqli_fetch_assoc($result))
 						{
 							$html_table = $this->sql_report('add_select_row', $query, $html_table, $row);
 						}
+						mysqli_free_result($result);
 					}
-					@mysqli_free_result($result);
 
 					if ($html_table)
 					{
@@ -418,7 +433,7 @@ class mysqli extends \phpbb\db\driver\mysql_base
 						if ($result = @mysqli_query($this->db_connect_id, 'SHOW PROFILE ALL;'))
 						{
 							$this->html_hold .= '<br />';
-							while ($row = @mysqli_fetch_assoc($result))
+							while ($row = mysqli_fetch_assoc($result))
 							{
 								// make <unknown> HTML safe
 								if (!empty($row['Source_function']))
@@ -436,8 +451,8 @@ class mysqli extends \phpbb\db\driver\mysql_base
 								}
 								$html_table = $this->sql_report('add_select_row', $query, $html_table, $row);
 							}
+							mysqli_free_result($result);
 						}
-						@mysqli_free_result($result);
 
 						if ($html_table)
 						{
@@ -455,14 +470,14 @@ class mysqli extends \phpbb\db\driver\mysql_base
 				$endtime = $endtime[0] + $endtime[1];
 
 				$result = @mysqli_query($this->db_connect_id, $query);
-				if ($result !== null)
+				if ($result)
 				{
-					while ($void = @mysqli_fetch_assoc($result))
+					while ($void = mysqli_fetch_assoc($result))
 					{
 						// Take the time spent on parsing rows into account
 					}
+					mysqli_free_result($result);
 				}
-				@mysqli_free_result($result);
 
 				$splittime = explode(' ', microtime());
 				$splittime = $splittime[0] + $splittime[1];
diff --git a/phpBB/phpbb/db/driver/oracle.php b/phpBB/phpbb/db/driver/oracle.php
index 6dcab5dd7d..54238a15ef 100644
--- a/phpBB/phpbb/db/driver/oracle.php
+++ b/phpBB/phpbb/db/driver/oracle.php
@@ -84,8 +84,6 @@ class oracle extends \phpbb\db\driver\driver
 		* but I assume its because the Oracle extension provides a direct method to access it
 		* without a query.
 		*/
-
-		$use_cache = false;
 /*
 		global $cache;
 
@@ -439,12 +437,17 @@ class oracle extends \phpbb\db\driver\driver
 					$this->sql_time += microtime(true) - $this->curtime;
 				}
 
+				if (!$this->query_result)
+				{
+					return false;
+				}
+
 				if ($cache && $cache_ttl)
 				{
 					$this->open_queries[(int) $this->query_result] = $this->query_result;
 					$this->query_result = $cache->sql_save($this, $query, $this->query_result, $cache_ttl);
 				}
-				else if (strpos($query, 'SELECT') === 0 && $this->query_result)
+				else if (strpos($query, 'SELECT') === 0)
 				{
 					$this->open_queries[(int) $this->query_result] = $this->query_result;
 				}
@@ -499,10 +502,10 @@ class oracle extends \phpbb\db\driver\driver
 			return $cache->sql_fetchrow($query_id);
 		}
 
-		if ($query_id !== false)
+		if ($query_id)
 		{
 			$row = array();
-			$result = @ocifetchinto($query_id, $row, OCI_ASSOC + OCI_RETURN_NULLS);
+			$result = ocifetchinto($query_id, $row, OCI_ASSOC + OCI_RETURN_NULLS);
 
 			if (!$result || !$row)
 			{
@@ -550,7 +553,7 @@ class oracle extends \phpbb\db\driver\driver
 			return $cache->sql_rowseek($rownum, $query_id);
 		}
 
-		if ($query_id === false)
+		if (!$query_id)
 		{
 			return false;
 		}
@@ -583,18 +586,24 @@ class oracle extends \phpbb\db\driver\driver
 			{
 				$query = 'SELECT ' . $tablename[1] . '_seq.currval FROM DUAL';
 				$stmt = @ociparse($this->db_connect_id, $query);
-				@ociexecute($stmt, OCI_DEFAULT);
+				if ($stmt)
+				{
+					$success = @ociexecute($stmt, OCI_DEFAULT);
 
-				$temp_result = @ocifetchinto($stmt, $temp_array, OCI_ASSOC + OCI_RETURN_NULLS);
-				@ocifreestatement($stmt);
+					if ($success)
+					{
+						$temp_result = ocifetchinto($stmt, $temp_array, OCI_ASSOC + OCI_RETURN_NULLS);
+						ocifreestatement($stmt);
 
-				if ($temp_result)
-				{
-					return $temp_array['CURRVAL'];
-				}
-				else
-				{
-					return false;
+						if ($temp_result)
+						{
+							return $temp_array['CURRVAL'];
+						}
+						else
+						{
+							return false;
+						}
+					}
 				}
 			}
 		}
@@ -622,7 +631,7 @@ class oracle extends \phpbb\db\driver\driver
 		if (isset($this->open_queries[(int) $query_id]))
 		{
 			unset($this->open_queries[(int) $query_id]);
-			return @ocifreestatement($query_id);
+			return ocifreestatement($query_id);
 		}
 
 		return false;
@@ -787,14 +796,20 @@ class oracle extends \phpbb\db\driver\driver
 				$endtime = $endtime[0] + $endtime[1];
 
 				$result = @ociparse($this->db_connect_id, $query);
-				$success = @ociexecute($result, OCI_DEFAULT);
-				$row = array();
-
-				while (@ocifetchinto($result, $row, OCI_ASSOC + OCI_RETURN_NULLS))
+				if ($result)
 				{
-					// Take the time spent on parsing rows into account
+					$success = @ociexecute($result, OCI_DEFAULT);
+					if ($success)
+					{
+						$row = array();
+
+						while (ocifetchinto($result, $row, OCI_ASSOC + OCI_RETURN_NULLS))
+						{
+							// Take the time spent on parsing rows into account
+						}
+						@ocifreestatement($result);
+					}
 				}
-				@ocifreestatement($result);
 
 				$splittime = explode(' ', microtime());
 				$splittime = $splittime[0] + $splittime[1];
diff --git a/phpBB/phpbb/db/driver/postgres.php b/phpBB/phpbb/db/driver/postgres.php
index a3b9aa4c6b..44476612c3 100644
--- a/phpBB/phpbb/db/driver/postgres.php
+++ b/phpBB/phpbb/db/driver/postgres.php
@@ -123,14 +123,17 @@ class postgres extends \phpbb\db\driver\driver
 		if (!$use_cache || empty($cache) || ($this->sql_server_version = $cache->get('pgsql_version')) === false)
 		{
 			$query_id = @pg_query($this->db_connect_id, 'SELECT VERSION() AS version');
-			$row = @pg_fetch_assoc($query_id, null);
-			@pg_free_result($query_id);
+			if ($query_id)
+			{
+				$row = pg_fetch_assoc($query_id, null);
+				pg_free_result($query_id);
 
-			$this->sql_server_version = (!empty($row['version'])) ? trim(substr($row['version'], 10)) : 0;
+				$this->sql_server_version = (!empty($row['version'])) ? trim(substr($row['version'], 10)) : 0;
 
-			if (!empty($cache) && $use_cache)
-			{
-				$cache->put('pgsql_version', $this->sql_server_version);
+				if (!empty($cache) && $use_cache)
+				{
+					$cache->put('pgsql_version', $this->sql_server_version);
+				}
 			}
 		}
 
@@ -200,12 +203,17 @@ class postgres extends \phpbb\db\driver\driver
 					$this->sql_time += microtime(true) - $this->curtime;
 				}
 
+				if (!$this->query_result)
+				{
+					return false;
+				}
+
 				if ($cache && $cache_ttl)
 				{
 					$this->open_queries[(int) $this->query_result] = $this->query_result;
 					$this->query_result = $cache->sql_save($this, $query, $this->query_result, $cache_ttl);
 				}
-				else if (strpos($query, 'SELECT') === 0 && $this->query_result)
+				else if (strpos($query, 'SELECT') === 0)
 				{
 					$this->open_queries[(int) $this->query_result] = $this->query_result;
 				}
@@ -275,7 +283,7 @@ class postgres extends \phpbb\db\driver\driver
 			return $cache->sql_fetchrow($query_id);
 		}
 
-		return ($query_id !== false) ? @pg_fetch_assoc($query_id, null) : false;
+		return ($query_id) ? pg_fetch_assoc($query_id, null) : false;
 	}
 
 	/**
@@ -295,7 +303,7 @@ class postgres extends \phpbb\db\driver\driver
 			return $cache->sql_rowseek($rownum, $query_id);
 		}
 
-		return ($query_id !== false) ? @pg_result_seek($query_id, $rownum) : false;
+		return ($query_id) ? @pg_result_seek($query_id, $rownum) : false;
 	}
 
 	/**
@@ -317,8 +325,8 @@ class postgres extends \phpbb\db\driver\driver
 					return false;
 				}
 
-				$temp_result = @pg_fetch_assoc($temp_q_id, null);
-				@pg_free_result($query_id);
+				$temp_result = pg_fetch_assoc($temp_q_id, null);
+				pg_free_result($query_id);
 
 				return ($temp_result) ? $temp_result['last_value'] : false;
 			}
@@ -347,7 +355,7 @@ class postgres extends \phpbb\db\driver\driver
 		if (isset($this->open_queries[(int) $query_id]))
 		{
 			unset($this->open_queries[(int) $query_id]);
-			return @pg_free_result($query_id);
+			return pg_free_result($query_id);
 		}
 
 		return false;
@@ -453,12 +461,12 @@ class postgres extends \phpbb\db\driver\driver
 
 					if ($result = @pg_query($this->db_connect_id, "EXPLAIN $explain_query"))
 					{
-						while ($row = @pg_fetch_assoc($result, null))
+						while ($row = pg_fetch_assoc($result, null))
 						{
 							$html_table = $this->sql_report('add_select_row', $query, $html_table, $row);
 						}
+						pg_free_result($result);
 					}
-					@pg_free_result($result);
 
 					if ($html_table)
 					{
@@ -473,11 +481,14 @@ class postgres extends \phpbb\db\driver\driver
 				$endtime = $endtime[0] + $endtime[1];
 
 				$result = @pg_query($this->db_connect_id, $query);
-				while ($void = @pg_fetch_assoc($result, null))
+				if ($result)
 				{
-					// Take the time spent on parsing rows into account
+					while ($void = pg_fetch_assoc($result, null))
+					{
+						// Take the time spent on parsing rows into account
+					}
+					pg_free_result($result);
 				}
-				@pg_free_result($result);
 
 				$splittime = explode(' ', microtime());
 				$splittime = $splittime[0] + $splittime[1];
diff --git a/phpBB/phpbb/db/driver/sqlite.php b/phpBB/phpbb/db/driver/sqlite.php
index d5da0e2438..8e205ebb81 100644
--- a/phpBB/phpbb/db/driver/sqlite.php
+++ b/phpBB/phpbb/db/driver/sqlite.php
@@ -70,13 +70,16 @@ class sqlite extends \phpbb\db\driver\driver
 		if (!$use_cache || empty($cache) || ($this->sql_server_version = $cache->get('sqlite_version')) === false)
 		{
 			$result = @sqlite_query('SELECT sqlite_version() AS version', $this->db_connect_id);
-			$row = @sqlite_fetch_array($result, SQLITE_ASSOC);
+			if ($result)
+			{
+				$row = sqlite_fetch_array($result, SQLITE_ASSOC);
 
-			$this->sql_server_version = (!empty($row['version'])) ? $row['version'] : 0;
+				$this->sql_server_version = (!empty($row['version'])) ? $row['version'] : 0;
 
-			if (!empty($cache) && $use_cache)
-			{
-				$cache->put('sqlite_version', $this->sql_server_version);
+				if (!empty($cache) && $use_cache)
+				{
+					$cache->put('sqlite_version', $this->sql_server_version);
+				}
 			}
 		}
 
@@ -145,14 +148,14 @@ class sqlite extends \phpbb\db\driver\driver
 					$this->sql_time += microtime(true) - $this->curtime;
 				}
 
-				if ($cache && $cache_ttl)
+				if (!$this->query_result)
 				{
-					$this->open_queries[(int) $this->query_result] = $this->query_result;
-					$this->query_result = $cache->sql_save($this, $query, $this->query_result, $cache_ttl);
+					return false;
 				}
-				else if (strpos($query, 'SELECT') === 0 && $this->query_result)
+
+				if ($cache && $cache_ttl)
 				{
-					$this->open_queries[(int) $this->query_result] = $this->query_result;
+					$this->query_result = $cache->sql_save($this, $query, $this->query_result, $cache_ttl);
 				}
 			}
 			else if (defined('DEBUG'))
@@ -211,7 +214,7 @@ class sqlite extends \phpbb\db\driver\driver
 			return $cache->sql_fetchrow($query_id);
 		}
 
-		return ($query_id !== false) ? @sqlite_fetch_array($query_id, SQLITE_ASSOC) : false;
+		return ($query_id) ? sqlite_fetch_array($query_id, SQLITE_ASSOC) : false;
 	}
 
 	/**
@@ -231,7 +234,7 @@ class sqlite extends \phpbb\db\driver\driver
 			return $cache->sql_rowseek($rownum, $query_id);
 		}
 
-		return ($query_id !== false) ? @sqlite_seek($query_id, $rownum) : false;
+		return ($query_id) ? @sqlite_seek($query_id, $rownum) : false;
 	}
 
 	/**
@@ -362,9 +365,12 @@ class sqlite extends \phpbb\db\driver\driver
 				$endtime = $endtime[0] + $endtime[1];
 
 				$result = @sqlite_query($query, $this->db_connect_id);
-				while ($void = @sqlite_fetch_array($result, SQLITE_ASSOC))
+				if ($result)
 				{
-					// Take the time spent on parsing rows into account
+					while ($void = sqlite_fetch_array($result, SQLITE_ASSOC))
+					{
+						// Take the time spent on parsing rows into account
+					}
 				}
 
 				$splittime = explode(' ', microtime());
diff --git a/phpBB/phpbb/db/driver/sqlite3.php b/phpBB/phpbb/db/driver/sqlite3.php
index cc3352af34..0508500c52 100644
--- a/phpBB/phpbb/db/driver/sqlite3.php
+++ b/phpBB/phpbb/db/driver/sqlite3.php
@@ -102,7 +102,7 @@ class sqlite3 extends \phpbb\db\driver\driver
 			break;
 
 			case 'rollback':
-				return $this->dbo->exec('ROLLBACK');
+				return @$this->dbo->exec('ROLLBACK');
 			break;
 		}
 
@@ -134,9 +134,26 @@ class sqlite3 extends \phpbb\db\driver\driver
 
 			if ($this->query_result === false)
 			{
+				if ($this->transaction === true && strpos($query, 'INSERT') === 0)
+				{
+					$query = preg_replace('/^INSERT INTO/', 'INSERT OR ROLLBACK INTO', $query);
+				}
+
 				if (($this->query_result = @$this->dbo->query($query)) === false)
 				{
-					$this->sql_error($query);
+					// Try to recover a lost database connection
+					if ($this->dbo && !@$this->dbo->lastErrorMsg())
+					{
+						if ($this->sql_connect($this->server, $this->user, '', $this->dbname))
+						{
+							$this->query_result = @$this->dbo->query($query);
+						}
+					}
+
+					if ($this->query_result === false)
+					{
+						$this->sql_error($query);
+					}
 				}
 
 				if (defined('DEBUG'))
@@ -148,6 +165,11 @@ class sqlite3 extends \phpbb\db\driver\driver
 					$this->sql_time += microtime(true) - $this->curtime;
 				}
 
+				if (!$this->query_result)
+				{
+					return false;
+				}
+
 				if ($cache && $cache_ttl)
 				{
 					$this->query_result = $cache->sql_save($this, $query, $this->query_result, $cache_ttl);
@@ -208,6 +230,7 @@ class sqlite3 extends \phpbb\db\driver\driver
 
 		if ($query_id === false)
 		{
+			/** @var \SQLite3Result $query_id */
 			$query_id = $this->query_result;
 		}
 
@@ -216,7 +239,7 @@ class sqlite3 extends \phpbb\db\driver\driver
 			return $cache->sql_fetchrow($query_id);
 		}
 
-		return is_object($query_id) ? $query_id->fetchArray(SQLITE3_ASSOC) : false;
+		return is_object($query_id) ? @$query_id->fetchArray(SQLITE3_ASSOC) : false;
 	}
 
 	/**
@@ -389,9 +412,12 @@ class sqlite3 extends \phpbb\db\driver\driver
 				$endtime = $endtime[0] + $endtime[1];
 
 				$result = $this->dbo->query($query);
-				while ($void = $result->fetchArray(SQLITE3_ASSOC))
+				if ($result)
 				{
-					// Take the time spent on parsing rows into account
+						while ($void = $result->fetchArray(SQLITE3_ASSOC))
+						{
+							// Take the time spent on parsing rows into account
+						}
 				}
 
 				$splittime = explode(' ', microtime());