1 files changed, 2554 insertions, 0 deletions
diff --git a/phpBB/phpbb/db/tools.php b/phpBB/phpbb/db/tools.php
new file mode 100644
index 0000000000..7616849465
--- /dev/null
+++ b/phpBB/phpbb/db/tools.php
@@ -0,0 +1,2554 @@
+<?php
+/**
+*
+* @package dbal
+* @copyright (c) 2007 phpBB Group
+* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2
+*
+*/
+
+namespace phpbb\db;
+
+/**
+* Database Tools for handling cross-db actions such as altering columns, etc.
+* Currently not supported is returning SQL for creating tables.
+*
+* @package dbal
+*/
+class tools
+{
+	/**
+	* Current sql layer
+	*/
+	var $sql_layer = '';
+
+	/**
+	* @var object DB object
+	*/
+	var $db = null;
+
+	/**
+	* The Column types for every database we support
+	* @var array
+	*/
+	var $dbms_type_map = array();
+
+	/**
+	* Get the column types for every database we support
+	*
+	* @return array
+	*/
+	public static function get_dbms_type_map()
+	{
+		return array(
+			'mysql_41'	=> array(
+				'INT:'		=> 'int(%d)',
+				'BINT'		=> 'bigint(20)',
+				'UINT'		=> 'mediumint(8) UNSIGNED',
+				'UINT:'		=> 'int(%d) UNSIGNED',
+				'TINT:'		=> 'tinyint(%d)',
+				'USINT'		=> 'smallint(4) UNSIGNED',
+				'BOOL'		=> 'tinyint(1) UNSIGNED',
+				'VCHAR'		=> 'varchar(255)',
+				'VCHAR:'	=> 'varchar(%d)',
+				'CHAR:'		=> 'char(%d)',
+				'XSTEXT'	=> 'text',
+				'XSTEXT_UNI'=> 'varchar(100)',
+				'STEXT'		=> 'text',
+				'STEXT_UNI'	=> 'varchar(255)',
+				'TEXT'		=> 'text',
+				'TEXT_UNI'	=> 'text',
+				'MTEXT'		=> 'mediumtext',
+				'MTEXT_UNI'	=> 'mediumtext',
+				'TIMESTAMP'	=> 'int(11) UNSIGNED',
+				'DECIMAL'	=> 'decimal(5,2)',
+				'DECIMAL:'	=> 'decimal(%d,2)',
+				'PDECIMAL'	=> 'decimal(6,3)',
+				'PDECIMAL:'	=> 'decimal(%d,3)',
+				'VCHAR_UNI'	=> 'varchar(255)',
+				'VCHAR_UNI:'=> 'varchar(%d)',
+				'VCHAR_CI'	=> 'varchar(255)',
+				'VARBINARY'	=> 'varbinary(255)',
+			),
+
+			'mysql_40'	=> array(
+				'INT:'		=> 'int(%d)',
+				'BINT'		=> 'bigint(20)',
+				'UINT'		=> 'mediumint(8) UNSIGNED',
+				'UINT:'		=> 'int(%d) UNSIGNED',
+				'TINT:'		=> 'tinyint(%d)',
+				'USINT'		=> 'smallint(4) UNSIGNED',
+				'BOOL'		=> 'tinyint(1) UNSIGNED',
+				'VCHAR'		=> 'varbinary(255)',
+				'VCHAR:'	=> 'varbinary(%d)',
+				'CHAR:'		=> 'binary(%d)',
+				'XSTEXT'	=> 'blob',
+				'XSTEXT_UNI'=> 'blob',
+				'STEXT'		=> 'blob',
+				'STEXT_UNI'	=> 'blob',
+				'TEXT'		=> 'blob',
+				'TEXT_UNI'	=> 'blob',
+				'MTEXT'		=> 'mediumblob',
+				'MTEXT_UNI'	=> 'mediumblob',
+				'TIMESTAMP'	=> 'int(11) UNSIGNED',
+				'DECIMAL'	=> 'decimal(5,2)',
+				'DECIMAL:'	=> 'decimal(%d,2)',
+				'PDECIMAL'	=> 'decimal(6,3)',
+				'PDECIMAL:'	=> 'decimal(%d,3)',
+				'VCHAR_UNI'	=> 'blob',
+				'VCHAR_UNI:'=> array('varbinary(%d)', 'limit' => array('mult', 3, 255, 'blob')),
+				'VCHAR_CI'	=> 'blob',
+				'VARBINARY'	=> 'varbinary(255)',
+			),
+
+			'firebird'	=> array(
+				'INT:'		=> 'INTEGER',
+				'BINT'		=> 'DOUBLE PRECISION',
+				'UINT'		=> 'INTEGER',
+				'UINT:'		=> 'INTEGER',
+				'TINT:'		=> 'INTEGER',
+				'USINT'		=> 'INTEGER',
+				'BOOL'		=> 'INTEGER',
+				'VCHAR'		=> 'VARCHAR(255) CHARACTER SET NONE',
+				'VCHAR:'	=> 'VARCHAR(%d) CHARACTER SET NONE',
+				'CHAR:'		=> 'CHAR(%d) CHARACTER SET NONE',
+				'XSTEXT'	=> 'BLOB SUB_TYPE TEXT CHARACTER SET NONE',
+				'STEXT'		=> 'BLOB SUB_TYPE TEXT CHARACTER SET NONE',
+				'TEXT'		=> 'BLOB SUB_TYPE TEXT CHARACTER SET NONE',
+				'MTEXT'		=> 'BLOB SUB_TYPE TEXT CHARACTER SET NONE',
+				'XSTEXT_UNI'=> 'VARCHAR(100) CHARACTER SET UTF8',
+				'STEXT_UNI'	=> 'VARCHAR(255) CHARACTER SET UTF8',
+				'TEXT_UNI'	=> 'BLOB SUB_TYPE TEXT CHARACTER SET UTF8',
+				'MTEXT_UNI'	=> 'BLOB SUB_TYPE TEXT CHARACTER SET UTF8',
+				'TIMESTAMP'	=> 'INTEGER',
+				'DECIMAL'	=> 'DOUBLE PRECISION',
+				'DECIMAL:'	=> 'DOUBLE PRECISION',
+				'PDECIMAL'	=> 'DOUBLE PRECISION',
+				'PDECIMAL:'	=> 'DOUBLE PRECISION',
+				'VCHAR_UNI'	=> 'VARCHAR(255) CHARACTER SET UTF8',
+				'VCHAR_UNI:'=> 'VARCHAR(%d) CHARACTER SET UTF8',
+				'VCHAR_CI'	=> 'VARCHAR(255) CHARACTER SET UTF8',
+				'VARBINARY'	=> 'CHAR(255) CHARACTER SET NONE',
+			),
+
+			'mssql'		=> array(
+				'INT:'		=> '[int]',
+				'BINT'		=> '[float]',
+				'UINT'		=> '[int]',
+				'UINT:'		=> '[int]',
+				'TINT:'		=> '[int]',
+				'USINT'		=> '[int]',
+				'BOOL'		=> '[int]',
+				'VCHAR'		=> '[varchar] (255)',
+				'VCHAR:'	=> '[varchar] (%d)',
+				'CHAR:'		=> '[char] (%d)',
+				'XSTEXT'	=> '[varchar] (1000)',
+				'STEXT'		=> '[varchar] (3000)',
+				'TEXT'		=> '[varchar] (8000)',
+				'MTEXT'		=> '[text]',
+				'XSTEXT_UNI'=> '[varchar] (100)',
+				'STEXT_UNI'	=> '[varchar] (255)',
+				'TEXT_UNI'	=> '[varchar] (4000)',
+				'MTEXT_UNI'	=> '[text]',
+				'TIMESTAMP'	=> '[int]',
+				'DECIMAL'	=> '[float]',
+				'DECIMAL:'	=> '[float]',
+				'PDECIMAL'	=> '[float]',
+				'PDECIMAL:'	=> '[float]',
+				'VCHAR_UNI'	=> '[varchar] (255)',
+				'VCHAR_UNI:'=> '[varchar] (%d)',
+				'VCHAR_CI'	=> '[varchar] (255)',
+				'VARBINARY'	=> '[varchar] (255)',
+			),
+
+			'mssqlnative'	=> array(
+				'INT:'		=> '[int]',
+				'BINT'		=> '[float]',
+				'UINT'		=> '[int]',
+				'UINT:'		=> '[int]',
+				'TINT:'		=> '[int]',
+				'USINT'		=> '[int]',
+				'BOOL'		=> '[int]',
+				'VCHAR'		=> '[varchar] (255)',
+				'VCHAR:'	=> '[varchar] (%d)',
+				'CHAR:'		=> '[char] (%d)',
+				'XSTEXT'	=> '[varchar] (1000)',
+				'STEXT'		=> '[varchar] (3000)',
+				'TEXT'		=> '[varchar] (8000)',
+				'MTEXT'		=> '[text]',
+				'XSTEXT_UNI'=> '[varchar] (100)',
+				'STEXT_UNI'	=> '[varchar] (255)',
+				'TEXT_UNI'	=> '[varchar] (4000)',
+				'MTEXT_UNI'	=> '[text]',
+				'TIMESTAMP'	=> '[int]',
+				'DECIMAL'	=> '[float]',
+				'DECIMAL:'	=> '[float]',
+				'PDECIMAL'	=> '[float]',
+				'PDECIMAL:'	=> '[float]',
+				'VCHAR_UNI'	=> '[varchar] (255)',
+				'VCHAR_UNI:'=> '[varchar] (%d)',
+				'VCHAR_CI'	=> '[varchar] (255)',
+				'VARBINARY'	=> '[varchar] (255)',
+			),
+
+			'oracle'	=> array(
+				'INT:'		=> 'number(%d)',
+				'BINT'		=> 'number(20)',
+				'UINT'		=> 'number(8)',
+				'UINT:'		=> 'number(%d)',
+				'TINT:'		=> 'number(%d)',
+				'USINT'		=> 'number(4)',
+				'BOOL'		=> 'number(1)',
+				'VCHAR'		=> 'varchar2(255)',
+				'VCHAR:'	=> 'varchar2(%d)',
+				'CHAR:'		=> 'char(%d)',
+				'XSTEXT'	=> 'varchar2(1000)',
+				'STEXT'		=> 'varchar2(3000)',
+				'TEXT'		=> 'clob',
+				'MTEXT'		=> 'clob',
+				'XSTEXT_UNI'=> 'varchar2(300)',
+				'STEXT_UNI'	=> 'varchar2(765)',
+				'TEXT_UNI'	=> 'clob',
+				'MTEXT_UNI'	=> 'clob',
+				'TIMESTAMP'	=> 'number(11)',
+				'DECIMAL'	=> 'number(5, 2)',
+				'DECIMAL:'	=> 'number(%d, 2)',
+				'PDECIMAL'	=> 'number(6, 3)',
+				'PDECIMAL:'	=> 'number(%d, 3)',
+				'VCHAR_UNI'	=> 'varchar2(765)',
+				'VCHAR_UNI:'=> array('varchar2(%d)', 'limit' => array('mult', 3, 765, 'clob')),
+				'VCHAR_CI'	=> 'varchar2(255)',
+				'VARBINARY'	=> 'raw(255)',
+			),
+
+			'sqlite'	=> array(
+				'INT:'		=> 'int(%d)',
+				'BINT'		=> 'bigint(20)',
+				'UINT'		=> 'INTEGER UNSIGNED', //'mediumint(8) UNSIGNED',
+				'UINT:'		=> 'INTEGER UNSIGNED', // 'int(%d) UNSIGNED',
+				'TINT:'		=> 'tinyint(%d)',
+				'USINT'		=> 'INTEGER UNSIGNED', //'mediumint(4) UNSIGNED',
+				'BOOL'		=> 'INTEGER UNSIGNED', //'tinyint(1) UNSIGNED',
+				'VCHAR'		=> 'varchar(255)',
+				'VCHAR:'	=> 'varchar(%d)',
+				'CHAR:'		=> 'char(%d)',
+				'XSTEXT'	=> 'text(65535)',
+				'STEXT'		=> 'text(65535)',
+				'TEXT'		=> 'text(65535)',
+				'MTEXT'		=> 'mediumtext(16777215)',
+				'XSTEXT_UNI'=> 'text(65535)',
+				'STEXT_UNI'	=> 'text(65535)',
+				'TEXT_UNI'	=> 'text(65535)',
+				'MTEXT_UNI'	=> 'mediumtext(16777215)',
+				'TIMESTAMP'	=> 'INTEGER UNSIGNED', //'int(11) UNSIGNED',
+				'DECIMAL'	=> 'decimal(5,2)',
+				'DECIMAL:'	=> 'decimal(%d,2)',
+				'PDECIMAL'	=> 'decimal(6,3)',
+				'PDECIMAL:'	=> 'decimal(%d,3)',
+				'VCHAR_UNI'	=> 'varchar(255)',
+				'VCHAR_UNI:'=> 'varchar(%d)',
+				'VCHAR_CI'	=> 'varchar(255)',
+				'VARBINARY'	=> 'blob',
+			),
+
+			'postgres'	=> array(
+				'INT:'		=> 'INT4',
+				'BINT'		=> 'INT8',
+				'UINT'		=> 'INT4', // unsigned
+				'UINT:'		=> 'INT4', // unsigned
+				'USINT'		=> 'INT2', // unsigned
+				'BOOL'		=> 'INT2', // unsigned
+				'TINT:'		=> 'INT2',
+				'VCHAR'		=> 'varchar(255)',
+				'VCHAR:'	=> 'varchar(%d)',
+				'CHAR:'		=> 'char(%d)',
+				'XSTEXT'	=> 'varchar(1000)',
+				'STEXT'		=> 'varchar(3000)',
+				'TEXT'		=> 'varchar(8000)',
+				'MTEXT'		=> 'TEXT',
+				'XSTEXT_UNI'=> 'varchar(100)',
+				'STEXT_UNI'	=> 'varchar(255)',
+				'TEXT_UNI'	=> 'varchar(4000)',
+				'MTEXT_UNI'	=> 'TEXT',
+				'TIMESTAMP'	=> 'INT4', // unsigned
+				'DECIMAL'	=> 'decimal(5,2)',
+				'DECIMAL:'	=> 'decimal(%d,2)',
+				'PDECIMAL'	=> 'decimal(6,3)',
+				'PDECIMAL:'	=> 'decimal(%d,3)',
+				'VCHAR_UNI'	=> 'varchar(255)',
+				'VCHAR_UNI:'=> 'varchar(%d)',
+				'VCHAR_CI'	=> 'varchar_ci',
+				'VARBINARY'	=> 'bytea',
+			),
+		);
+	}
+
+	/**
+	* A list of types being unsigned for better reference in some db's
+	* @var array
+	*/
+	var $unsigned_types = array('UINT', 'UINT:', 'USINT', 'BOOL', 'TIMESTAMP');
+
+	/**
+	* A list of supported DBMS. We change this class to support more DBMS, the DBMS itself only need to follow some rules.
+	* @var array
+	*/
+	var $supported_dbms = array('firebird', 'mssql', 'mssqlnative', 'mysql_40', 'mysql_41', 'oracle', 'postgres', 'sqlite');
+
+	/**
+	* This is set to true if user only wants to return the 'to-be-executed' SQL statement(s) (as an array).
+	* This mode has no effect on some methods (inserting of data for example). This is expressed within the methods command.
+	*/
+	var $return_statements = false;
+
+	/**
+	* Constructor. Set DB Object and set {@link $return_statements return_statements}.
+	*
+	* @param \phpbb\db\driver\driver_interface	$db					Database connection
+	* @param bool		$return_statements	True if only statements should be returned and no SQL being executed
+	*/
+	public function __construct(\phpbb\db\driver\driver_interface $db, $return_statements = false)
+	{
+		$this->db = $db;
+		$this->return_statements = $return_statements;
+
+		$this->dbms_type_map = self::get_dbms_type_map();
+
+		// Determine mapping database type
+		switch ($this->db->sql_layer)
+		{
+			case 'mysql':
+				$this->sql_layer = 'mysql_40';
+			break;
+
+			case 'mysql4':
+				if (version_compare($this->db->sql_server_info(true), '4.1.3', '>='))
+				{
+					$this->sql_layer = 'mysql_41';
+				}
+				else
+				{
+					$this->sql_layer = 'mysql_40';
+				}
+			break;
+
+			case 'mysqli':
+				$this->sql_layer = 'mysql_41';
+			break;
+
+			case 'mssql':
+			case 'mssql_odbc':
+				$this->sql_layer = 'mssql';
+			break;
+
+			case 'mssqlnative':
+				$this->sql_layer = 'mssqlnative';
+			break;
+
+			default:
+				$this->sql_layer = $this->db->sql_layer;
+			break;
+		}
+	}
+
+	/**
+	* Setter for {@link $return_statements return_statements}.
+	*
+	* @param bool $return_statements True if SQL should not be executed but returned as strings
+	* @return null
+	*/
+	public function set_return_statements($return_statements)
+	{
+		$this->return_statements = $return_statements;
+	}
+
+	/**
+	* Gets a list of tables in the database.
+	*
+	* @return array		Array of table names  (all lower case)
+	*/
+	function sql_list_tables()
+	{
+		switch ($this->db->sql_layer)
+		{
+			case 'mysql':
+			case 'mysql4':
+			case 'mysqli':
+				$sql = 'SHOW TABLES';
+			break;
+
+			case 'sqlite':
+				$sql = 'SELECT name
+					FROM sqlite_master
+					WHERE type = "table"';
+			break;
+
+			case 'mssql':
+			case 'mssql_odbc':
+			case 'mssqlnative':
+				$sql = "SELECT name
+					FROM sysobjects
+					WHERE type='U'";
+			break;
+
+			case 'postgres':
+				$sql = 'SELECT relname
+					FROM pg_stat_user_tables';
+			break;
+
+			case 'firebird':
+				$sql = 'SELECT rdb$relation_name
+					FROM rdb$relations
+					WHERE rdb$view_source is null
+						AND rdb$system_flag = 0';
+			break;
+
+			case 'oracle':
+				$sql = 'SELECT table_name
+					FROM USER_TABLES';
+			break;
+		}
+
+		$result = $this->db->sql_query($sql);
+
+		$tables = array();
+		while ($row = $this->db->sql_fetchrow($result))
+		{
+			$name = current($row);
+			$tables[$name] = $name;
+		}
+		$this->db->sql_freeresult($result);
+
+		return $tables;
+	}
+
+	/**
+	* Check if table exists
+	*
+	*
+	* @param string	$table_name	The table name to check for
+	* @return bool true if table exists, else false
+	*/
+	function sql_table_exists($table_name)
+	{
+		$this->db->sql_return_on_error(true);
+		$result = $this->db->sql_query_limit('SELECT * FROM ' . $table_name, 1);
+		$this->db->sql_return_on_error(false);
+
+		if ($result)
+		{
+			$this->db->sql_freeresult($result);
+			return true;
+		}
+
+		return false;
+	}
+
+	/**
+	* Create SQL Table
+	*
+	* @param string	$table_name	The table name to create
+	* @param array	$table_data	Array containing table data.
+	* @return array	Statements if $return_statements is true.
+	*/
+	function sql_create_table($table_name, $table_data)
+	{
+		// holds the DDL for a column
+		$columns = $statements = array();
+
+		if ($this->sql_table_exists($table_name))
+		{
+			return $this->_sql_run_sql($statements);
+		}
+
+		// Begin transaction
+		$statements[] = 'begin';
+
+		// Determine if we have created a PRIMARY KEY in the earliest
+		$primary_key_gen = false;
+
+		// Determine if the table requires a sequence
+		$create_sequence = false;
+
+		// Begin table sql statement
+		switch ($this->sql_layer)
+		{
+			case 'mssql':
+			case 'mssqlnative':
+				$table_sql = 'CREATE TABLE [' . $table_name . '] (' . "\n";
+			break;
+
+			default:
+				$table_sql = 'CREATE TABLE ' . $table_name . ' (' . "\n";
+			break;
+		}
+
+		if ($this->sql_layer == 'mssql' || $this->sql_layer == 'mssqlnative')
+		{
+			if (!isset($table_data['PRIMARY_KEY']))
+			{
+				$table_data['COLUMNS']['mssqlindex'] = array('UINT', null, 'auto_increment');
+				$table_data['PRIMARY_KEY'] = 'mssqlindex';
+			}
+		}
+
+		// Iterate through the columns to create a table
+		foreach ($table_data['COLUMNS'] as $column_name => $column_data)
+		{
+			// here lies an array, filled with information compiled on the column's data
+			$prepared_column = $this->sql_prepare_column_data($table_name, $column_name, $column_data);
+
+			if (isset($prepared_column['auto_increment']) && $prepared_column['auto_increment'] && strlen($column_name) > 26) // "${column_name}_gen"
+			{
+				trigger_error("Index name '${column_name}_gen' on table '$table_name' is too long. The maximum auto increment column length is 26 characters.", E_USER_ERROR);
+			}
+
+			// here we add the definition of the new column to the list of columns
+			switch ($this->sql_layer)
+			{
+				case 'mssql':
+				case 'mssqlnative':
+					$columns[] = "\t [{$column_name}] " . $prepared_column['column_type_sql_default'];
+				break;
+
+				default:
+					$columns[] = "\t {$column_name} " . $prepared_column['column_type_sql'];
+				break;
+			}
+
+			// see if we have found a primary key set due to a column definition if we have found it, we can stop looking
+			if (!$primary_key_gen)
+			{
+				$primary_key_gen = isset($prepared_column['primary_key_set']) && $prepared_column['primary_key_set'];
+			}
+
+			// create sequence DDL based off of the existance of auto incrementing columns
+			if (!$create_sequence && isset($prepared_column['auto_increment']) && $prepared_column['auto_increment'])
+			{
+				$create_sequence = $column_name;
+			}
+		}
+
+		// this makes up all the columns in the create table statement
+		$table_sql .= implode(",\n", $columns);
+
+		// Close the table for two DBMS and add to the statements
+		switch ($this->sql_layer)
+		{
+			case 'firebird':
+			case 'mssql':
+			case 'mssqlnative':
+				$table_sql .= "\n);";
+				$statements[] = $table_sql;
+			break;
+		}
+
+		// we have yet to create a primary key for this table,
+		// this means that we can add the one we really wanted instead
+		if (!$primary_key_gen)
+		{
+			// Write primary key
+			if (isset($table_data['PRIMARY_KEY']))
+			{
+				if (!is_array($table_data['PRIMARY_KEY']))
+				{
+					$table_data['PRIMARY_KEY'] = array($table_data['PRIMARY_KEY']);
+				}
+
+				switch ($this->sql_layer)
+				{
+					case 'mysql_40':
+					case 'mysql_41':
+					case 'postgres':
+					case 'sqlite':
+						$table_sql .= ",\n\t PRIMARY KEY (" . implode(', ', $table_data['PRIMARY_KEY']) . ')';
+					break;
+
+					case 'firebird':
+					case 'mssql':
+					case 'mssqlnative':
+						// We need the data here
+						$old_return_statements = $this->return_statements;
+						$this->return_statements = true;
+
+						$primary_key_stmts = $this->sql_create_primary_key($table_name, $table_data['PRIMARY_KEY']);
+						foreach ($primary_key_stmts as $pk_stmt)
+						{
+							$statements[] = $pk_stmt;
+						}
+
+						$this->return_statements = $old_return_statements;
+					break;
+
+					case 'oracle':
+						$table_sql .= ",\n\t CONSTRAINT pk_{$table_name} PRIMARY KEY (" . implode(', ', $table_data['PRIMARY_KEY']) . ')';
+					break;
+				}
+			}
+		}
+
+		// close the table
+		switch ($this->sql_layer)
+		{
+			case 'mysql_41':
+				// make sure the table is in UTF-8 mode
+				$table_sql .= "\n) CHARACTER SET `utf8` COLLATE `utf8_bin`;";
+				$statements[] = $table_sql;
+			break;
+
+			case 'mysql_40':
+			case 'sqlite':
+				$table_sql .= "\n);";
+				$statements[] = $table_sql;
+			break;
+
+			case 'postgres':
+				// do we need to add a sequence for auto incrementing columns?
+				if ($create_sequence)
+				{
+					$statements[] = "CREATE SEQUENCE {$table_name}_seq;";
+				}
+
+				$table_sql .= "\n);";
+				$statements[] = $table_sql;
+			break;
+
+			case 'oracle':
+				$table_sql .= "\n)";
+				$statements[] = $table_sql;
+
+				// do we need to add a sequence and a tigger for auto incrementing columns?
+				if ($create_sequence)
+				{
+					// create the actual sequence
+					$statements[] = "CREATE SEQUENCE {$table_name}_seq";
+
+					// the trigger is the mechanism by which we increment the counter
+					$trigger = "CREATE OR REPLACE TRIGGER t_{$table_name}\n";
+					$trigger .= "BEFORE INSERT ON {$table_name}\n";
+					$trigger .= "FOR EACH ROW WHEN (\n";
+					$trigger .= "\tnew.{$create_sequence} IS NULL OR new.{$create_sequence} = 0\n";
+					$trigger .= ")\n";
+					$trigger .= "BEGIN\n";
+					$trigger .= "\tSELECT {$table_name}_seq.nextval\n";
+					$trigger .= "\tINTO :new.{$create_sequence}\n";
+					$trigger .= "\tFROM dual;\n";
+					$trigger .= "END;";
+
+					$statements[] = $trigger;
+				}
+			break;
+
+			case 'firebird':
+				if ($create_sequence)
+				{
+					$statements[] = "CREATE GENERATOR {$table_name}_gen;";
+					$statements[] = "SET GENERATOR {$table_name}_gen TO 0;";
+
+					$trigger = "CREATE TRIGGER t_$table_name FOR $table_name\n";
+					$trigger .= "BEFORE INSERT\nAS\nBEGIN\n";
+					$trigger .= "\tNEW.{$create_sequence} = GEN_ID({$table_name}_gen, 1);\nEND;";
+					$statements[] = $trigger;
+				}
+			break;
+		}
+
+		// Write Keys
+		if (isset($table_data['KEYS']))
+		{
+			foreach ($table_data['KEYS'] as $key_name => $key_data)
+			{
+				if (!is_array($key_data[1]))
+				{
+					$key_data[1] = array($key_data[1]);
+				}
+
+				$old_return_statements = $this->return_statements;
+				$this->return_statements = true;
+
+				$key_stmts = ($key_data[0] == 'UNIQUE') ? $this->sql_create_unique_index($table_name, $key_name, $key_data[1]) : $this->sql_create_index($table_name, $key_name, $key_data[1]);
+
+				foreach ($key_stmts as $key_stmt)
+				{
+					$statements[] = $key_stmt;
+				}
+
+				$this->return_statements = $old_return_statements;
+			}
+		}
+
+		// Commit Transaction
+		$statements[] = 'commit';
+
+		return $this->_sql_run_sql($statements);
+	}
+
+	/**
+	* Handle passed database update array.
+	* Expected structure...
+	* Key being one of the following
+	*	drop_tables: Drop tables
+	*	add_tables: Add tables
+	*	change_columns: Column changes (only type, not name)
+	*	add_columns: Add columns to a table
+	*	drop_keys: Dropping keys
+	*	drop_columns: Removing/Dropping columns
+	*	add_primary_keys: adding primary keys
+	*	add_unique_index: adding an unique index
+	*	add_index: adding an index (can be column:index_size if you need to provide size)
+	*
+	* The values are in this format:
+	*		{TABLE NAME}		=> array(
+	*			{COLUMN NAME}		=> array({COLUMN TYPE}, {DEFAULT VALUE}, {OPTIONAL VARIABLES}),
+	*			{KEY/INDEX NAME}	=> array({COLUMN NAMES}),
+	*		)
+	*
+	* For more information have a look at /develop/create_schema_files.php (only available through SVN)
+	*/
+	function perform_schema_changes($schema_changes)
+	{
+		if (empty($schema_changes))
+		{
+			return;
+		}
+
+		$statements = array();
+		$sqlite = false;
+
+		// For SQLite we need to perform the schema changes in a much more different way
+		if ($this->db->sql_layer == 'sqlite' && $this->return_statements)
+		{
+			$sqlite_data = array();
+			$sqlite = true;
+		}
+
+		// Drop tables?
+		if (!empty($schema_changes['drop_tables']))
+		{
+			foreach ($schema_changes['drop_tables'] as $table)
+			{
+				// only drop table if it exists
+				if ($this->sql_table_exists($table))
+				{
+					$result = $this->sql_table_drop($table);
+					if ($this->return_statements)
+					{
+						$statements = array_merge($statements, $result);
+					}
+				}
+			}
+		}
+
+		// Add tables?
+		if (!empty($schema_changes['add_tables']))
+		{
+			foreach ($schema_changes['add_tables'] as $table => $table_data)
+			{
+				$result = $this->sql_create_table($table, $table_data);
+				if ($this->return_statements)
+				{
+					$statements = array_merge($statements, $result);
+				}
+			}
+		}
+
+		// Change columns?
+		if (!empty($schema_changes['change_columns']))
+		{
+			foreach ($schema_changes['change_columns'] as $table => $columns)
+			{
+				foreach ($columns as $column_name => $column_data)
+				{
+					// If the column exists we change it, else we add it ;)
+					if ($column_exists = $this->sql_column_exists($table, $column_name))
+					{
+						$result = $this->sql_column_change($table, $column_name, $column_data, true);
+					}
+					else
+					{
+						$result = $this->sql_column_add($table, $column_name, $column_data, true);
+					}
+
+					if ($sqlite)
+					{
+						if ($column_exists)
+						{
+							$sqlite_data[$table]['change_columns'][] = $result;
+						}
+						else
+						{
+							$sqlite_data[$table]['add_columns'][] = $result;
+						}
+					}
+					else if ($this->return_statements)
+					{
+						$statements = array_merge($statements, $result);
+					}
+				}
+			}
+		}
+
+		// Add columns?
+		if (!empty($schema_changes['add_columns']))
+		{
+			foreach ($schema_changes['add_columns'] as $table => $columns)
+			{
+				foreach ($columns as $column_name => $column_data)
+				{
+					// Only add the column if it does not exist yet
+					if ($column_exists = $this->sql_column_exists($table, $column_name))
+					{
+						continue;
+						// This is commented out here because it can take tremendous time on updates
+//						$result = $this->sql_column_change($table, $column_name, $column_data, true);
+					}
+					else
+					{
+						$result = $this->sql_column_add($table, $column_name, $column_data, true);
+					}
+
+					if ($sqlite)
+					{
+						if ($column_exists)
+						{
+							continue;
+//							$sqlite_data[$table]['change_columns'][] = $result;
+						}
+						else
+						{
+							$sqlite_data[$table]['add_columns'][] = $result;
+						}
+					}
+					else if ($this->return_statements)
+					{
+						$statements = array_merge($statements, $result);
+					}
+				}
+			}
+		}
+
+		// Remove keys?
+		if (!empty($schema_changes['drop_keys']))
+		{
+			foreach ($schema_changes['drop_keys'] as $table => $indexes)
+			{
+				foreach ($indexes as $index_name)
+				{
+					if (!$this->sql_index_exists($table, $index_name))
+					{
+						continue;
+					}
+
+					$result = $this->sql_index_drop($table, $index_name);
+
+					if ($this->return_statements)
+					{
+						$statements = array_merge($statements, $result);
+					}
+				}
+			}
+		}
+
+		// Drop columns?
+		if (!empty($schema_changes['drop_columns']))
+		{
+			foreach ($schema_changes['drop_columns'] as $table => $columns)
+			{
+				foreach ($columns as $column)
+				{
+					// Only remove the column if it exists...
+					if ($this->sql_column_exists($table, $column))
+					{
+						$result = $this->sql_column_remove($table, $column, true);
+
+						if ($sqlite)
+						{
+							$sqlite_data[$table]['drop_columns'][] = $result;
+						}
+						else if ($this->return_statements)
+						{
+							$statements = array_merge($statements, $result);
+						}
+					}
+				}
+			}
+		}
+
+		// Add primary keys?
+		if (!empty($schema_changes['add_primary_keys']))
+		{
+			foreach ($schema_changes['add_primary_keys'] as $table => $columns)
+			{
+				$result = $this->sql_create_primary_key($table, $columns, true);
+
+				if ($sqlite)
+				{
+					$sqlite_data[$table]['primary_key'] = $result;
+				}
+				else if ($this->return_statements)
+				{
+					$statements = array_merge($statements, $result);
+				}
+			}
+		}
+
+		// Add unqiue indexes?
+		if (!empty($schema_changes['add_unique_index']))
+		{
+			foreach ($schema_changes['add_unique_index'] as $table => $index_array)
+			{
+				foreach ($index_array as $index_name => $column)
+				{
+					if ($this->sql_unique_index_exists($table, $index_name))
+					{
+						continue;
+					}
+
+					$result = $this->sql_create_unique_index($table, $index_name, $column);
+
+					if ($this->return_statements)
+					{
+						$statements = array_merge($statements, $result);
+					}
+				}
+			}
+		}
+
+		// Add indexes?
+		if (!empty($schema_changes['add_index']))
+		{
+			foreach ($schema_changes['add_index'] as $table => $index_array)
+			{
+				foreach ($index_array as $index_name => $column)
+				{
+					if ($this->sql_index_exists($table, $index_name))
+					{
+						continue;
+					}
+
+					$result = $this->sql_create_index($table, $index_name, $column);
+
+					if ($this->return_statements)
+					{
+						$statements = array_merge($statements, $result);
+					}
+				}
+			}
+		}
+
+		if ($sqlite)
+		{
+			foreach ($sqlite_data as $table_name => $sql_schema_changes)
+			{
+				// Create temporary table with original data
+				$statements[] = 'begin';
+
+				$sql = "SELECT sql
+					FROM sqlite_master
+					WHERE type = 'table'
+						AND name = '{$table_name}'
+					ORDER BY type DESC, name;";
+				$result = $this->db->sql_query($sql);
+
+				if (!$result)
+				{
+					continue;
+				}
+
+				$row = $this->db->sql_fetchrow($result);
+				$this->db->sql_freeresult($result);
+
+				// Create a backup table and populate it, destroy the existing one
+				$statements[] = preg_replace('#CREATE\s+TABLE\s+"?' . $table_name . '"?#i', 'CREATE TEMPORARY TABLE ' . $table_name . '_temp', $row['sql']);
+				$statements[] = 'INSERT INTO ' . $table_name . '_temp SELECT * FROM ' . $table_name;
+				$statements[] = 'DROP TABLE ' . $table_name;
+
+				// Get the columns...
+				preg_match('#\((.*)\)#s', $row['sql'], $matches);
+
+				$plain_table_cols = trim($matches[1]);
+				$new_table_cols = preg_split('/,(?![\s\w]+\))/m', $plain_table_cols);
+				$column_list = array();
+
+				foreach ($new_table_cols as $declaration)
+				{
+					$entities = preg_split('#\s+#', trim($declaration));
+					if ($entities[0] == 'PRIMARY')
+					{
+						continue;
+					}
+					$column_list[] = $entities[0];
+				}
+
+				// note down the primary key notation because sqlite only supports adding it to the end for the new table
+				$primary_key = false;
+				$_new_cols = array();
+
+				foreach ($new_table_cols as $key => $declaration)
+				{
+					$entities = preg_split('#\s+#', trim($declaration));
+					if ($entities[0] == 'PRIMARY')
+					{
+						$primary_key = $declaration;
+						continue;
+					}
+					$_new_cols[] = $declaration;
+				}
+
+				$new_table_cols = $_new_cols;
+
+				// First of all... change columns
+				if (!empty($sql_schema_changes['change_columns']))
+				{
+					foreach ($sql_schema_changes['change_columns'] as $column_sql)
+					{
+						foreach ($new_table_cols as $key => $declaration)
+						{
+							$entities = preg_split('#\s+#', trim($declaration));
+							if (strpos($column_sql, $entities[0] . ' ') === 0)
+							{
+								$new_table_cols[$key] = $column_sql;
+							}
+						}
+					}
+				}
+
+				if (!empty($sql_schema_changes['add_columns']))
+				{
+					foreach ($sql_schema_changes['add_columns'] as $column_sql)
+					{
+						$new_table_cols[] = $column_sql;
+					}
+				}
+
+				// Now drop them...
+				if (!empty($sql_schema_changes['drop_columns']))
+				{
+					foreach ($sql_schema_changes['drop_columns'] as $column_name)
+					{
+						// Remove from column list...
+						$new_column_list = array();
+						foreach ($column_list as $key => $value)
+						{
+							if ($value === $column_name)
+							{
+								continue;
+							}
+
+							$new_column_list[] = $value;
+						}
+
+						$column_list = $new_column_list;
+
+						// Remove from table...
+						$_new_cols = array();
+						foreach ($new_table_cols as $key => $declaration)
+						{
+							$entities = preg_split('#\s+#', trim($declaration));
+							if (strpos($column_name . ' ', $entities[0] . ' ') === 0)
+							{
+								continue;
+							}
+							$_new_cols[] = $declaration;
+						}
+						$new_table_cols = $_new_cols;
+					}
+				}
+
+				// Primary key...
+				if (!empty($sql_schema_changes['primary_key']))
+				{
+					$new_table_cols[] = 'PRIMARY KEY (' . implode(', ', $sql_schema_changes['primary_key']) . ')';
+				}
+				// Add a new one or the old primary key
+				else if ($primary_key !== false)
+				{
+					$new_table_cols[] = $primary_key;
+				}
+
+				$columns = implode(',', $column_list);
+
+				// create a new table and fill it up. destroy the temp one
+				$statements[] = 'CREATE TABLE ' . $table_name . ' (' . implode(',', $new_table_cols) . ');';
+				$statements[] = 'INSERT INTO ' . $table_name . ' (' . $columns . ') SELECT ' . $columns . ' FROM ' . $table_name . '_temp;';
+				$statements[] = 'DROP TABLE ' . $table_name . '_temp';
+
+				$statements[] = 'commit';
+			}
+		}
+
+		if ($this->return_statements)
+		{
+			return $statements;
+		}
+	}
+
+	/**
+	* Gets a list of columns of a table.
+	*
+	* @param string $table		Table name
+	*
+	* @return array				Array of column names (all lower case)
+	*/
+	function sql_list_columns($table)
+	{
+		$columns = array();
+
+		switch ($this->sql_layer)
+		{
+			case 'mysql_40':
+			case 'mysql_41':
+				$sql = "SHOW COLUMNS FROM $table";
+			break;
+
+			// PostgreSQL has a way of doing this in a much simpler way but would
+			// not allow us to support all versions of PostgreSQL
+			case 'postgres':
+				$sql = "SELECT a.attname
+					FROM pg_class c, pg_attribute a
+					WHERE c.relname = '{$table}'
+						AND a.attnum > 0
+						AND a.attrelid = c.oid";
+			break;
+
+			// same deal with PostgreSQL, we must perform more complex operations than
+			// we technically could
+			case 'mssql':
+			case 'mssqlnative':
+				$sql = "SELECT c.name
+					FROM syscolumns c
+					LEFT JOIN sysobjects o ON c.id = o.id
+					WHERE o.name = '{$table}'";
+			break;
+
+			case 'oracle':
+				$sql = "SELECT column_name
+					FROM user_tab_columns
+					WHERE LOWER(table_name) = '" . strtolower($table) . "'";
+			break;
+
+			case 'firebird':
+				$sql = "SELECT RDB\$FIELD_NAME as FNAME
+					FROM RDB\$RELATION_FIELDS
+					WHERE RDB\$RELATION_NAME = '" . strtoupper($table) . "'";
+			break;
+
+			case 'sqlite':
+				$sql = "SELECT sql
+					FROM sqlite_master
+					WHERE type = 'table'
+						AND name = '{$table}'";
+
+				$result = $this->db->sql_query($sql);
+
+				if (!$result)
+				{
+					return false;
+				}
+
+				$row = $this->db->sql_fetchrow($result);
+				$this->db->sql_freeresult($result);
+
+				preg_match('#\((.*)\)#s', $row['sql'], $matches);
+
+				$cols = trim($matches[1]);
+				$col_array = preg_split('/,(?![\s\w]+\))/m', $cols);
+
+				foreach ($col_array as $declaration)
+				{
+					$entities = preg_split('#\s+#', trim($declaration));
+					if ($entities[0] == 'PRIMARY')
+					{
+						continue;
+					}
+
+					$column = strtolower($entities[0]);
+					$columns[$column] = $column;
+				}
+
+				return $columns;
+			break;
+		}
+
+		$result = $this->db->sql_query($sql);
+
+		while ($row = $this->db->sql_fetchrow($result))
+		{
+			$column = strtolower(current($row));
+			$columns[$column] = $column;
+		}
+		$this->db->sql_freeresult($result);
+
+		return $columns;
+	}
+
+	/**
+	* Check whether a specified column exist in a table
+	*
+	* @param string	$table			Table to check
+	* @param string	$column_name	Column to check
+	*
+	* @return bool		True if column exists, false otherwise
+	*/
+	function sql_column_exists($table, $column_name)
+	{
+		$columns = $this->sql_list_columns($table);
+
+		return isset($columns[$column_name]);
+	}
+
+	/**
+	* Check if a specified index exists in table. Does not return PRIMARY KEY and UNIQUE indexes.
+	*
+	* @param string	$table_name		Table to check the index at
+	* @param string	$index_name		The index name to check
+	*
+	* @return bool True if index exists, else false
+	*/
+	function sql_index_exists($table_name, $index_name)
+	{
+		if ($this->sql_layer == 'mssql' || $this->sql_layer == 'mssqlnative')
+		{
+			$sql = "EXEC sp_statistics '$table_name'";
+			$result = $this->db->sql_query($sql);
+
+			while ($row = $this->db->sql_fetchrow($result))
+			{
+				if ($row['TYPE'] == 3)
+				{
+					if (strtolower($row['INDEX_NAME']) == strtolower($index_name))
+					{
+						$this->db->sql_freeresult($result);
+						return true;
+					}
+				}
+			}
+			$this->db->sql_freeresult($result);
+
+			return false;
+		}
+
+		switch ($this->sql_layer)
+		{
+			case 'firebird':
+				$sql = "SELECT LOWER(RDB\$INDEX_NAME) as index_name
+					FROM RDB\$INDICES
+					WHERE RDB\$RELATION_NAME = '" . strtoupper($table_name) . "'
+						AND RDB\$UNIQUE_FLAG IS NULL
+						AND RDB\$FOREIGN_KEY IS NULL";
+				$col = 'index_name';
+			break;
+
+			case 'postgres':
+				$sql = "SELECT ic.relname as index_name
+					FROM pg_class bc, pg_class ic, pg_index i
+					WHERE (bc.oid = i.indrelid)
+						AND (ic.oid = i.indexrelid)
+						AND (bc.relname = '" . $table_name . "')
+						AND (i.indisunique != 't')
+						AND (i.indisprimary != 't')";
+				$col = 'index_name';
+			break;
+
+			case 'mysql_40':
+			case 'mysql_41':
+				$sql = 'SHOW KEYS
+					FROM ' . $table_name;
+				$col = 'Key_name';
+			break;
+
+			case 'oracle':
+				$sql = "SELECT index_name
+					FROM user_indexes
+					WHERE table_name = '" . strtoupper($table_name) . "'
+						AND generated = 'N'
+						AND uniqueness = 'NONUNIQUE'";
+				$col = 'index_name';
+			break;
+
+			case 'sqlite':
+				$sql = "PRAGMA index_list('" . $table_name . "');";
+				$col = 'name';
+			break;
+		}
+
+		$result = $this->db->sql_query($sql);
+		while ($row = $this->db->sql_fetchrow($result))
+		{
+			if (($this->sql_layer == 'mysql_40' || $this->sql_layer == 'mysql_41') && !$row['Non_unique'])
+			{
+				continue;
+			}
+
+			// These DBMS prefix index name with the table name
+			switch ($this->sql_layer)
+			{
+				case 'firebird':
+				case 'oracle':
+				case 'postgres':
+				case 'sqlite':
+					$row[$col] = substr($row[$col], strlen($table_name) + 1);
+				break;
+			}
+
+			if (strtolower($row[$col]) == strtolower($index_name))
+			{
+				$this->db->sql_freeresult($result);
+				return true;
+			}
+		}
+		$this->db->sql_freeresult($result);
+
+		return false;
+	}
+
+	/**
+	* Check if a specified index exists in table. Does not return PRIMARY KEY and UNIQUE indexes.
+	*
+	* @param string	$table_name		Table to check the index at
+	* @param string	$index_name		The index name to check
+	*
+	* @return bool True if index exists, else false
+	*/
+	function sql_unique_index_exists($table_name, $index_name)
+	{
+		if ($this->sql_layer == 'mssql' || $this->sql_layer == 'mssqlnative')
+		{
+			$sql = "EXEC sp_statistics '$table_name'";
+			$result = $this->db->sql_query($sql);
+
+			while ($row = $this->db->sql_fetchrow($result))
+			{
+				// Usually NON_UNIQUE is the column we want to check, but we allow for both
+				if ($row['TYPE'] == 3)
+				{
+					if (strtolower($row['INDEX_NAME']) == strtolower($index_name))
+					{
+						$this->db->sql_freeresult($result);
+						return true;
+					}
+				}
+			}
+			$this->db->sql_freeresult($result);
+			return false;
+		}
+
+		switch ($this->sql_layer)
+		{
+			case 'firebird':
+				$sql = "SELECT LOWER(RDB\$INDEX_NAME) as index_name
+					FROM RDB\$INDICES
+					WHERE RDB\$RELATION_NAME = '" . strtoupper($table_name) . "'
+						AND RDB\$UNIQUE_FLAG IS NOT NULL
+						AND RDB\$FOREIGN_KEY IS NULL";
+				$col = 'index_name';
+			break;
+
+			case 'postgres':
+				$sql = "SELECT ic.relname as index_name, i.indisunique
+					FROM pg_class bc, pg_class ic, pg_index i
+					WHERE (bc.oid = i.indrelid)
+						AND (ic.oid = i.indexrelid)
+						AND (bc.relname = '" . $table_name . "')
+						AND (i.indisprimary != 't')";
+				$col = 'index_name';
+			break;
+
+			case 'mysql_40':
+			case 'mysql_41':
+				$sql = 'SHOW KEYS
+					FROM ' . $table_name;
+				$col = 'Key_name';
+			break;
+
+			case 'oracle':
+				$sql = "SELECT index_name, table_owner
+					FROM user_indexes
+					WHERE table_name = '" . strtoupper($table_name) . "'
+						AND generated = 'N'
+						AND uniqueness = 'UNIQUE'";
+				$col = 'index_name';
+			break;
+
+			case 'sqlite':
+				$sql = "PRAGMA index_list('" . $table_name . "');";
+				$col = 'name';
+			break;
+		}
+
+		$result = $this->db->sql_query($sql);
+		while ($row = $this->db->sql_fetchrow($result))
+		{
+			if (($this->sql_layer == 'mysql_40' || $this->sql_layer == 'mysql_41') && ($row['Non_unique'] || $row[$col] == 'PRIMARY'))
+			{
+				continue;
+			}
+
+			if ($this->sql_layer == 'sqlite' && !$row['unique'])
+			{
+				continue;
+			}
+
+			if ($this->sql_layer == 'postgres' && $row['indisunique'] != 't')
+			{
+				continue;
+			}
+
+			// These DBMS prefix index name with the table name
+			switch ($this->sql_layer)
+			{
+				case 'oracle':
+					// Two cases here... prefixed with U_[table_owner] and not prefixed with table_name
+					if (strpos($row[$col], 'U_') === 0)
+					{
+						$row[$col] = substr($row[$col], strlen('U_' . $row['table_owner']) + 1);
+					}
+					else if (strpos($row[$col], strtoupper($table_name)) === 0)
+					{
+						$row[$col] = substr($row[$col], strlen($table_name) + 1);
+					}
+				break;
+
+				case 'firebird':
+				case 'postgres':
+				case 'sqlite':
+					$row[$col] = substr($row[$col], strlen($table_name) + 1);
+				break;
+			}
+
+			if (strtolower($row[$col]) == strtolower($index_name))
+			{
+				$this->db->sql_freeresult($result);
+				return true;
+			}
+		}
+		$this->db->sql_freeresult($result);
+
+		return false;
+	}
+
+	/**
+	* Private method for performing sql statements (either execute them or return them)
+	* @access private
+	*/
+	function _sql_run_sql($statements)
+	{
+		if ($this->return_statements)
+		{
+			return $statements;
+		}
+
+		// We could add error handling here...
+		foreach ($statements as $sql)
+		{
+			if ($sql === 'begin')
+			{
+				$this->db->sql_transaction('begin');
+			}
+			else if ($sql === 'commit')
+			{
+				$this->db->sql_transaction('commit');
+			}
+			else
+			{
+				$this->db->sql_query($sql);
+			}
+		}
+
+		return true;
+	}
+
+	/**
+	* Function to prepare some column information for better usage
+	* @access private
+	*/
+	function sql_prepare_column_data($table_name, $column_name, $column_data)
+	{
+		if (strlen($column_name) > 30)
+		{
+			trigger_error("Column name '$column_name' on table '$table_name' is too long. The maximum is 30 characters.", E_USER_ERROR);
+		}
+
+		// Get type
+		list($column_type, $orig_column_type) = $this->get_column_type($column_data[0]);
+
+		// Adjust default value if db-dependent specified
+		if (is_array($column_data[1]))
+		{
+			$column_data[1] = (isset($column_data[1][$this->sql_layer])) ? $column_data[1][$this->sql_layer] : $column_data[1]['default'];
+		}
+
+		$sql = '';
+
+		$return_array = array();
+
+		switch ($this->sql_layer)
+		{
+			case 'firebird':
+				$sql .= " {$column_type} ";
+				$return_array['column_type_sql_type'] = " {$column_type} ";
+
+				if (!is_null($column_data[1]))
+				{
+					$sql .= 'DEFAULT ' . ((is_numeric($column_data[1])) ? $column_data[1] : "'{$column_data[1]}'") . ' ';
+					$return_array['column_type_sql_default'] = ((is_numeric($column_data[1])) ? $column_data[1] : "'{$column_data[1]}'") . ' ';
+				}
+
+				$sql .= 'NOT NULL';
+
+				// This is a UNICODE column and thus should be given it's fair share
+				if (preg_match('/^X?STEXT_UNI|VCHAR_(CI|UNI:?)/', $column_data[0]))
+				{
+					$sql .= ' COLLATE UNICODE';
+				}
+
+				$return_array['auto_increment'] = false;
+				if (isset($column_data[2]) && $column_data[2] == 'auto_increment')
+				{
+					$return_array['auto_increment'] = true;
+				}
+
+			break;
+
+			case 'mssql':
+			case 'mssqlnative':
+				$sql .= " {$column_type} ";
+				$sql_default = " {$column_type} ";
+
+				// For adding columns we need the default definition
+				if (!is_null($column_data[1]))
+				{
+					// For hexadecimal values do not use single quotes
+					if (strpos($column_data[1], '0x') === 0)
+					{
+						$return_array['default'] = 'DEFAULT (' . $column_data[1] . ') ';
+						$sql_default .= $return_array['default'];
+					}
+					else
+					{
+						$return_array['default'] = 'DEFAULT (' . ((is_numeric($column_data[1])) ? $column_data[1] : "'{$column_data[1]}'") . ') ';
+						$sql_default .= $return_array['default'];
+					}
+				}
+
+				if (isset($column_data[2]) && $column_data[2] == 'auto_increment')
+				{
+//					$sql .= 'IDENTITY (1, 1) ';
+					$sql_default .= 'IDENTITY (1, 1) ';
+				}
+
+				$return_array['textimage'] = $column_type === '[text]';
+
+				$sql .= 'NOT NULL';
+				$sql_default .= 'NOT NULL';
+
+				$return_array['column_type_sql_default'] = $sql_default;
+
+			break;
+
+			case 'mysql_40':
+			case 'mysql_41':
+				$sql .= " {$column_type} ";
+
+				// For hexadecimal values do not use single quotes
+				if (!is_null($column_data[1]) && substr($column_type, -4) !== 'text' && substr($column_type, -4) !== 'blob')
+				{
+					$sql .= (strpos($column_data[1], '0x') === 0) ? "DEFAULT {$column_data[1]} " : "DEFAULT '{$column_data[1]}' ";
+				}
+				$sql .= 'NOT NULL';
+
+				if (isset($column_data[2]))
+				{
+					if ($column_data[2] == 'auto_increment')
+					{
+						$sql .= ' auto_increment';
+					}
+					else if ($this->sql_layer === 'mysql_41' && $column_data[2] == 'true_sort')
+					{
+						$sql .= ' COLLATE utf8_unicode_ci';
+					}
+				}
+
+			break;
+
+			case 'oracle':
+				$sql .= " {$column_type} ";
+				$sql .= (!is_null($column_data[1])) ? "DEFAULT '{$column_data[1]}' " : '';
+
+				// In Oracle empty strings ('') are treated as NULL.
+				// Therefore in oracle we allow NULL's for all DEFAULT '' entries
+				// Oracle does not like setting NOT NULL on a column that is already NOT NULL (this happens only on number fields)
+				if (!preg_match('/number/i', $column_type))
+				{
+					$sql .= ($column_data[1] === '') ? '' : 'NOT NULL';
+				}
+
+				$return_array['auto_increment'] = false;
+				if (isset($column_data[2]) && $column_data[2] == 'auto_increment')
+				{
+					$return_array['auto_increment'] = true;
+				}
+
+			break;
+
+			case 'postgres':
+				$return_array['column_type'] = $column_type;
+
+				$sql .= " {$column_type} ";
+
+				$return_array['auto_increment'] = false;
+				if (isset($column_data[2]) && $column_data[2] == 'auto_increment')
+				{
+					$default_val = "nextval('{$table_name}_seq')";
+					$return_array['auto_increment'] = true;
+				}
+				else if (!is_null($column_data[1]))
+				{
+					$default_val = "'" . $column_data[1] . "'";
+					$return_array['null'] = 'NOT NULL';
+					$sql .= 'NOT NULL ';
+				}
+
+				$return_array['default'] = $default_val;
+
+				$sql .= "DEFAULT {$default_val}";
+
+				// Unsigned? Then add a CHECK contraint
+				if (in_array($orig_column_type, $this->unsigned_types))
+				{
+					$return_array['constraint'] = "CHECK ({$column_name} >= 0)";
+					$sql .= " CHECK ({$column_name} >= 0)";
+				}
+
+			break;
+
+			case 'sqlite':
+				$return_array['primary_key_set'] = false;
+				if (isset($column_data[2]) && $column_data[2] == 'auto_increment')
+				{
+					$sql .= ' INTEGER PRIMARY KEY';
+					$return_array['primary_key_set'] = true;
+				}
+				else
+				{
+					$sql .= ' ' . $column_type;
+				}
+
+				$sql .= ' NOT NULL ';
+				$sql .= (!is_null($column_data[1])) ? "DEFAULT '{$column_data[1]}'" : '';
+
+			break;
+		}
+
+		$return_array['column_type_sql'] = $sql;
+
+		return $return_array;
+	}
+
+	/**
+	* Get the column's database type from the type map
+	*
+	* @param string $column_map_type
+	* @return array		column type for this database
+	*					and map type without length
+	*/
+	function get_column_type($column_map_type)
+	{
+		if (strpos($column_map_type, ':') !== false)
+		{
+			list($orig_column_type, $column_length) = explode(':', $column_map_type);
+			if (!is_array($this->dbms_type_map[$this->sql_layer][$orig_column_type . ':']))
+			{
+				$column_type = sprintf($this->dbms_type_map[$this->sql_layer][$orig_column_type . ':'], $column_length);
+			}
+			else
+			{
+				if (isset($this->dbms_type_map[$this->sql_layer][$orig_column_type . ':']['rule']))
+				{
+					switch ($this->dbms_type_map[$this->sql_layer][$orig_column_type . ':']['rule'][0])
+					{
+						case 'div':
+							$column_length /= $this->dbms_type_map[$this->sql_layer][$orig_column_type . ':']['rule'][1];
+							$column_length = ceil($column_length);
+							$column_type = sprintf($this->dbms_type_map[$this->sql_layer][$orig_column_type . ':'][0], $column_length);
+						break;
+					}
+				}
+
+				if (isset($this->dbms_type_map[$this->sql_layer][$orig_column_type . ':']['limit']))
+				{
+					switch ($this->dbms_type_map[$this->sql_layer][$orig_column_type . ':']['limit'][0])
+					{
+						case 'mult':
+							$column_length *= $this->dbms_type_map[$this->sql_layer][$orig_column_type . ':']['limit'][1];
+							if ($column_length > $this->dbms_type_map[$this->sql_layer][$orig_column_type . ':']['limit'][2])
+							{
+								$column_type = $this->dbms_type_map[$this->sql_layer][$orig_column_type . ':']['limit'][3];
+							}
+							else
+							{
+								$column_type = sprintf($this->dbms_type_map[$this->sql_layer][$orig_column_type . ':'][0], $column_length);
+							}
+						break;
+					}
+				}
+			}
+			$orig_column_type .= ':';
+		}
+		else
+		{
+			$orig_column_type = $column_map_type;
+			$column_type = $this->dbms_type_map[$this->sql_layer][$column_map_type];
+		}
+
+		return array($column_type, $orig_column_type);
+	}
+
+	/**
+	* Add new column
+	*/
+	function sql_column_add($table_name, $column_name, $column_data, $inline = false)
+	{
+		$column_data = $this->sql_prepare_column_data($table_name, $column_name, $column_data);
+		$statements = array();
+
+		switch ($this->sql_layer)
+		{
+			case 'firebird':
+				// Does not support AFTER statement, only POSITION (and there you need the column position)
+				$statements[] = 'ALTER TABLE ' . $table_name . ' ADD "' . strtoupper($column_name) . '" ' . $column_data['column_type_sql'];
+			break;
+
+			case 'mssql':
+			case 'mssqlnative':
+				// Does not support AFTER, only through temporary table
+				$statements[] = 'ALTER TABLE [' . $table_name . '] ADD [' . $column_name . '] ' . $column_data['column_type_sql_default'];
+			break;
+
+			case 'mysql_40':
+			case 'mysql_41':
+				$after = (!empty($column_data['after'])) ? ' AFTER ' . $column_data['after'] : '';
+				$statements[] = 'ALTER TABLE `' . $table_name . '` ADD COLUMN `' . $column_name . '` ' . $column_data['column_type_sql'] . $after;
+			break;
+
+			case 'oracle':
+				// Does not support AFTER, only through temporary table
+				$statements[] = 'ALTER TABLE ' . $table_name . ' ADD ' . $column_name . ' ' . $column_data['column_type_sql'];
+			break;
+
+			case 'postgres':
+				// Does not support AFTER, only through temporary table
+				if (version_compare($this->db->sql_server_info(true), '8.0', '>='))
+				{
+					$statements[] = 'ALTER TABLE ' . $table_name . ' ADD COLUMN "' . $column_name . '" ' . $column_data['column_type_sql'];
+				}
+				else
+				{
+					// old versions cannot add columns with default and null information
+					$statements[] = 'ALTER TABLE ' . $table_name . ' ADD COLUMN "' . $column_name . '" ' . $column_data['column_type'] . ' ' . $column_data['constraint'];
+
+					if (isset($column_data['null']))
+					{
+						if ($column_data['null'] == 'NOT NULL')
+						{
+							$statements[] = 'ALTER TABLE ' . $table_name . ' ALTER COLUMN ' . $column_name . ' SET NOT NULL';
+						}
+					}
+
+					if (isset($column_data['default']))
+					{
+						$statements[] = 'ALTER TABLE ' . $table_name . ' ALTER COLUMN ' . $column_name . ' SET DEFAULT ' . $column_data['default'];
+					}
+				}
+
+			break;
+
+			case 'sqlite':
+
+				if ($inline && $this->return_statements)
+				{
+					return $column_name . ' ' . $column_data['column_type_sql'];
+				}
+
+				if (version_compare(sqlite_libversion(), '3.0') == -1)
+				{
+					$sql = "SELECT sql
+						FROM sqlite_master
+						WHERE type = 'table'
+							AND name = '{$table_name}'
+						ORDER BY type DESC, name;";
+					$result = $this->db->sql_query($sql);
+
+					if (!$result)
+					{
+						break;
+					}
+
+					$row = $this->db->sql_fetchrow($result);
+					$this->db->sql_freeresult($result);
+
+					$statements[] = 'begin';
+
+					// Create a backup table and populate it, destroy the existing one
+					$statements[] = preg_replace('#CREATE\s+TABLE\s+"?' . $table_name . '"?#i', 'CREATE TEMPORARY TABLE ' . $table_name . '_temp', $row['sql']);
+					$statements[] = 'INSERT INTO ' . $table_name . '_temp SELECT * FROM ' . $table_name;
+					$statements[] = 'DROP TABLE ' . $table_name;
+
+					preg_match('#\((.*)\)#s', $row['sql'], $matches);
+
+					$new_table_cols = trim($matches[1]);
+					$old_table_cols = preg_split('/,(?![\s\w]+\))/m', $new_table_cols);
+					$column_list = array();
+
+					foreach ($old_table_cols as $declaration)
+					{
+						$entities = preg_split('#\s+#', trim($declaration));
+						if ($entities[0] == 'PRIMARY')
+						{
+							continue;
+						}
+						$column_list[] = $entities[0];
+					}
+
+					$columns = implode(',', $column_list);
+
+					$new_table_cols = $column_name . ' ' . $column_data['column_type_sql'] . ',' . $new_table_cols;
+
+					// create a new table and fill it up. destroy the temp one
+					$statements[] = 'CREATE TABLE ' . $table_name . ' (' . $new_table_cols . ');';
+					$statements[] = 'INSERT INTO ' . $table_name . ' (' . $columns . ') SELECT ' . $columns . ' FROM ' . $table_name . '_temp;';
+					$statements[] = 'DROP TABLE ' . $table_name . '_temp';
+
+					$statements[] = 'commit';
+				}
+				else
+				{
+					$statements[] = 'ALTER TABLE ' . $table_name . ' ADD ' . $column_name . ' [' . $column_data['column_type_sql'] . ']';
+				}
+			break;
+		}
+
+		return $this->_sql_run_sql($statements);
+	}
+
+	/**
+	* Drop column
+	*/
+	function sql_column_remove($table_name, $column_name, $inline = false)
+	{
+		$statements = array();
+
+		switch ($this->sql_layer)
+		{
+			case 'firebird':
+				$statements[] = 'ALTER TABLE ' . $table_name . ' DROP "' . strtoupper($column_name) . '"';
+			break;
+
+			case 'mssql':
+			case 'mssqlnative':
+				$sql = "SELECT CAST(SERVERPROPERTY('productversion') AS VARCHAR(25)) AS mssql_version";
+				$result = $this->db->sql_query($sql);
+				$row = $this->db->sql_fetchrow($result);
+				$this->db->sql_freeresult($result);
+
+				// Remove default constraints
+				if ($row['mssql_version'][0] == '8')	// SQL Server 2000
+				{
+					// http://msdn.microsoft.com/en-us/library/aa175912%28v=sql.80%29.aspx
+					// Deprecated in SQL Server 2005
+					$statements[] = "DECLARE @drop_default_name VARCHAR(100), @cmd VARCHAR(1000)
+						SET @drop_default_name =
+							(SELECT so.name FROM sysobjects so
+							JOIN sysconstraints sc ON so.id = sc.constid
+							WHERE object_name(so.parent_obj) = '{$table_name}'
+								AND so.xtype = 'D'
+								AND sc.colid = (SELECT colid FROM syscolumns
+									WHERE id = object_id('{$table_name}')
+										AND name = '{$column_name}'))
+						IF @drop_default_name <> ''
+						BEGIN
+							SET @cmd = 'ALTER TABLE [{$table_name}] DROP CONSTRAINT [' + @drop_default_name + ']'
+							EXEC(@cmd)
+						END";
+				}
+				else
+				{
+					$sql = "SELECT dobj.name AS def_name
+					FROM sys.columns col 
+						LEFT OUTER JOIN sys.objects dobj ON (dobj.object_id = col.default_object_id AND dobj.type = 'D')
+					WHERE col.object_id = object_id('{$table_name}') 
+					AND col.name = '{$column_name}'
+					AND dobj.name IS NOT NULL";
+					$result = $this->db->sql_query($sql);
+					$row = $this->db->sql_fetchrow($result);
+					$this->db->sql_freeresult($result);
+
+					if ($row)
+					{
+						$statements[] = 'ALTER TABLE [' . $table_name . '] DROP CONSTRAINT [' . $row['def_name'] . ']';
+					}
+				}
+
+				$statements[] = 'ALTER TABLE [' . $table_name . '] DROP COLUMN [' . $column_name . ']';
+			break;
+
+			case 'mysql_40':
+			case 'mysql_41':
+				$statements[] = 'ALTER TABLE `' . $table_name . '` DROP COLUMN `' . $column_name . '`';
+			break;
+
+			case 'oracle':
+				$statements[] = 'ALTER TABLE ' . $table_name . ' DROP COLUMN ' . $column_name;
+			break;
+
+			case 'postgres':
+				$statements[] = 'ALTER TABLE ' . $table_name . ' DROP COLUMN "' . $column_name . '"';
+			break;
+
+			case 'sqlite':
+
+				if ($inline && $this->return_statements)
+				{
+					return $column_name;
+				}
+
+				if (version_compare(sqlite_libversion(), '3.0') == -1)
+				{
+					$sql = "SELECT sql
+						FROM sqlite_master
+						WHERE type = 'table'
+							AND name = '{$table_name}'
+						ORDER BY type DESC, name;";
+					$result = $this->db->sql_query($sql);
+
+					if (!$result)
+					{
+						break;
+					}
+
+					$row = $this->db->sql_fetchrow($result);
+					$this->db->sql_freeresult($result);
+
+					$statements[] = 'begin';
+
+					// Create a backup table and populate it, destroy the existing one
+					$statements[] = preg_replace('#CREATE\s+TABLE\s+"?' . $table_name . '"?#i', 'CREATE TEMPORARY TABLE ' . $table_name . '_temp', $row['sql']);
+					$statements[] = 'INSERT INTO ' . $table_name . '_temp SELECT * FROM ' . $table_name;
+					$statements[] = 'DROP TABLE ' . $table_name;
+
+					preg_match('#\((.*)\)#s', $row['sql'], $matches);
+
+					$new_table_cols = trim($matches[1]);
+					$old_table_cols = preg_split('/,(?![\s\w]+\))/m', $new_table_cols);
+					$column_list = array();
+
+					foreach ($old_table_cols as $declaration)
+					{
+						$entities = preg_split('#\s+#', trim($declaration));
+						if ($entities[0] == 'PRIMARY' || $entities[0] === $column_name)
+						{
+							continue;
+						}
+						$column_list[] = $entities[0];
+					}
+
+					$columns = implode(',', $column_list);
+
+					$new_table_cols = preg_replace('/' . $column_name . '[^,]+(?:,|$)/m', '', $new_table_cols);
+
+					// create a new table and fill it up. destroy the temp one
+					$statements[] = 'CREATE TABLE ' . $table_name . ' (' . $new_table_cols . ');';
+					$statements[] = 'INSERT INTO ' . $table_name . ' (' . $columns . ') SELECT ' . $columns . ' FROM ' . $table_name . '_temp;';
+					$statements[] = 'DROP TABLE ' . $table_name . '_temp';
+
+					$statements[] = 'commit';
+				}
+				else
+				{
+					$statements[] = 'ALTER TABLE ' . $table_name . ' DROP COLUMN ' . $column_name;
+				}
+			break;
+		}
+
+		return $this->_sql_run_sql($statements);
+	}
+
+	/**
+	* Drop Index
+	*/
+	function sql_index_drop($table_name, $index_name)
+	{
+		$statements = array();
+
+		switch ($this->sql_layer)
+		{
+			case 'mssql':
+			case 'mssqlnative':
+				$statements[] = 'DROP INDEX ' . $table_name . '.' . $index_name;
+			break;
+
+			case 'mysql_40':
+			case 'mysql_41':
+				$statements[] = 'DROP INDEX ' . $index_name . ' ON ' . $table_name;
+			break;
+
+			case 'firebird':
+			case 'oracle':
+			case 'postgres':
+			case 'sqlite':
+				$statements[] = 'DROP INDEX ' . $table_name . '_' . $index_name;
+			break;
+		}
+
+		return $this->_sql_run_sql($statements);
+	}
+
+	/**
+	* Drop Table
+	*/
+	function sql_table_drop($table_name)
+	{
+		$statements = array();
+
+		if (!$this->sql_table_exists($table_name))
+		{
+			return $this->_sql_run_sql($statements);
+		}
+
+		// the most basic operation, get rid of the table
+		$statements[] = 'DROP TABLE ' . $table_name;
+
+		switch ($this->sql_layer)
+		{
+			case 'firebird':
+				$sql = 'SELECT RDB$GENERATOR_NAME as gen
+					FROM RDB$GENERATORS
+					WHERE RDB$SYSTEM_FLAG = 0
+						AND RDB$GENERATOR_NAME = \'' . strtoupper($table_name) . "_GEN'";
+				$result = $this->db->sql_query($sql);
+
+				// does a generator exist?
+				if ($row = $this->db->sql_fetchrow($result))
+				{
+					$statements[] = "DROP GENERATOR {$row['gen']};";
+				}
+				$this->db->sql_freeresult($result);
+			break;
+
+			case 'oracle':
+				$sql = 'SELECT A.REFERENCED_NAME
+					FROM USER_DEPENDENCIES A, USER_TRIGGERS B
+					WHERE A.REFERENCED_TYPE = \'SEQUENCE\'
+						AND A.NAME = B.TRIGGER_NAME
+						AND B.TABLE_NAME = \'' . strtoupper($table_name) . "'";
+				$result = $this->db->sql_query($sql);
+
+				// any sequences ref'd to this table's triggers?
+				while ($row = $this->db->sql_fetchrow($result))
+				{
+					$statements[] = "DROP SEQUENCE {$row['referenced_name']}";
+				}
+				$this->db->sql_freeresult($result);
+			break;
+
+			case 'postgres':
+				// PGSQL does not "tightly" bind sequences and tables, we must guess...
+				$sql = "SELECT relname
+					FROM pg_class
+					WHERE relkind = 'S'
+						AND relname = '{$table_name}_seq'";
+				$result = $this->db->sql_query($sql);
+
+				// We don't even care about storing the results. We already know the answer if we get rows back.
+				if ($this->db->sql_fetchrow($result))
+				{
+					$statements[] =  "DROP SEQUENCE {$table_name}_seq;\n";
+				}
+				$this->db->sql_freeresult($result);
+			break;
+		}
+
+		return $this->_sql_run_sql($statements);
+	}
+
+	/**
+	* Add primary key
+	*/
+	function sql_create_primary_key($table_name, $column, $inline = false)
+	{
+		$statements = array();
+
+		switch ($this->sql_layer)
+		{
+			case 'firebird':
+			case 'postgres':
+			case 'mysql_40':
+			case 'mysql_41':
+				$statements[] = 'ALTER TABLE ' . $table_name . ' ADD PRIMARY KEY (' . implode(', ', $column) . ')';
+			break;
+
+			case 'mssql':
+			case 'mssqlnative':
+				$sql = "ALTER TABLE [{$table_name}] WITH NOCHECK ADD ";
+				$sql .= "CONSTRAINT [PK_{$table_name}] PRIMARY KEY  CLUSTERED (";
+				$sql .= '[' . implode("],\n\t\t[", $column) . ']';
+				$sql .= ')';
+
+				$statements[] = $sql;
+			break;
+
+			case 'oracle':
+				$statements[] = 'ALTER TABLE ' . $table_name . 'add CONSTRAINT pk_' . $table_name . ' PRIMARY KEY (' . implode(', ', $column) . ')';
+			break;
+
+			case 'sqlite':
+
+				if ($inline && $this->return_statements)
+				{
+					return $column;
+				}
+
+				$sql = "SELECT sql
+					FROM sqlite_master
+					WHERE type = 'table'
+						AND name = '{$table_name}'
+					ORDER BY type DESC, name;";
+				$result = $this->db->sql_query($sql);
+
+				if (!$result)
+				{
+					break;
+				}
+
+				$row = $this->db->sql_fetchrow($result);
+				$this->db->sql_freeresult($result);
+
+				$statements[] = 'begin';
+
+				// Create a backup table and populate it, destroy the existing one
+				$statements[] = preg_replace('#CREATE\s+TABLE\s+"?' . $table_name . '"?#i', 'CREATE TEMPORARY TABLE ' . $table_name . '_temp', $row['sql']);
+				$statements[] = 'INSERT INTO ' . $table_name . '_temp SELECT * FROM ' . $table_name;
+				$statements[] = 'DROP TABLE ' . $table_name;
+
+				preg_match('#\((.*)\)#s', $row['sql'], $matches);
+
+				$new_table_cols = trim($matches[1]);
+				$old_table_cols = preg_split('/,(?![\s\w]+\))/m', $new_table_cols);
+				$column_list = array();
+
+				foreach ($old_table_cols as $declaration)
+				{
+					$entities = preg_split('#\s+#', trim($declaration));
+					if ($entities[0] == 'PRIMARY')
+					{
+						continue;
+					}
+					$column_list[] = $entities[0];
+				}
+
+				$columns = implode(',', $column_list);
+
+				// create a new table and fill it up. destroy the temp one
+				$statements[] = 'CREATE TABLE ' . $table_name . ' (' . $new_table_cols . ', PRIMARY KEY (' . implode(', ', $column) . '));';
+				$statements[] = 'INSERT INTO ' . $table_name . ' (' . $columns . ') SELECT ' . $columns . ' FROM ' . $table_name . '_temp;';
+				$statements[] = 'DROP TABLE ' . $table_name . '_temp';
+
+				$statements[] = 'commit';
+			break;
+		}
+
+		return $this->_sql_run_sql($statements);
+	}
+
+	/**
+	* Add unique index
+	*/
+	function sql_create_unique_index($table_name, $index_name, $column)
+	{
+		$statements = array();
+
+		$table_prefix = substr(CONFIG_TABLE, 0, -6); // strlen(config)
+		if (strlen($table_name . $index_name) - strlen($table_prefix) > 24)
+		{
+			$max_length = strlen($table_prefix) + 24;
+			trigger_error("Index name '{$table_name}_$index_name' on table '$table_name' is too long. The maximum is $max_length characters.", E_USER_ERROR);
+		}
+
+		switch ($this->sql_layer)
+		{
+			case 'firebird':
+			case 'postgres':
+			case 'oracle':
+			case 'sqlite':
+				$statements[] = 'CREATE UNIQUE INDEX ' . $table_name . '_' . $index_name . ' ON ' . $table_name . '(' . implode(', ', $column) . ')';
+			break;
+
+			case 'mysql_40':
+			case 'mysql_41':
+				$statements[] = 'ALTER TABLE ' . $table_name . ' ADD UNIQUE INDEX ' . $index_name . '(' . implode(', ', $column) . ')';
+			break;
+
+			case 'mssql':
+			case 'mssqlnative':
+				$statements[] = 'CREATE UNIQUE INDEX [' . $index_name . '] ON [' . $table_name . ']([' . implode('], [', $column) . '])';
+			break;
+		}
+
+		return $this->_sql_run_sql($statements);
+	}
+
+	/**
+	* Add index
+	*/
+	function sql_create_index($table_name, $index_name, $column)
+	{
+		$statements = array();
+
+		$table_prefix = substr(CONFIG_TABLE, 0, -6); // strlen(config)
+		if (strlen($table_name . $index_name) - strlen($table_prefix) > 24)
+		{
+			$max_length = strlen($table_prefix) + 24;
+			trigger_error("Index name '{$table_name}_$index_name' on table '$table_name' is too long. The maximum is $max_length characters.", E_USER_ERROR);
+		}
+
+		// remove index length unless MySQL4
+		if ('mysql_40' != $this->sql_layer)
+		{
+			$column = preg_replace('#:.*$#', '', $column);
+		}
+
+		switch ($this->sql_layer)
+		{
+			case 'firebird':
+			case 'postgres':
+			case 'oracle':
+			case 'sqlite':
+				$statements[] = 'CREATE INDEX ' . $table_name . '_' . $index_name . ' ON ' . $table_name . '(' . implode(', ', $column) . ')';
+			break;
+
+			case 'mysql_40':
+				// add index size to definition as required by MySQL4
+				foreach ($column as $i => $col)
+				{
+					if (false !== strpos($col, ':'))
+					{
+						list($col, $index_size) = explode(':', $col);
+						$column[$i] = "$col($index_size)";
+					}
+				}
+			// no break
+			case 'mysql_41':
+				$statements[] = 'ALTER TABLE ' . $table_name . ' ADD INDEX ' . $index_name . '(' . implode(', ', $column) . ')';
+			break;
+
+			case 'mssql':
+			case 'mssqlnative':
+				$statements[] = 'CREATE INDEX [' . $index_name . '] ON [' . $table_name . ']([' . implode('], [', $column) . '])';
+			break;
+		}
+
+		return $this->_sql_run_sql($statements);
+	}
+
+	/**
+	* List all of the indices that belong to a table,
+	* does not count:
+	* * UNIQUE indices
+	* * PRIMARY keys
+	*/
+	function sql_list_index($table_name)
+	{
+		$index_array = array();
+
+		if ($this->sql_layer == 'mssql' || $this->sql_layer == 'mssqlnative')
+		{
+			$sql = "EXEC sp_statistics '$table_name'";
+			$result = $this->db->sql_query($sql);
+			while ($row = $this->db->sql_fetchrow($result))
+			{
+				if ($row['TYPE'] == 3)
+				{
+					$index_array[] = $row['INDEX_NAME'];
+				}
+			}
+			$this->db->sql_freeresult($result);
+		}
+		else
+		{
+			switch ($this->sql_layer)
+			{
+				case 'firebird':
+					$sql = "SELECT LOWER(RDB\$INDEX_NAME) as index_name
+						FROM RDB\$INDICES
+						WHERE RDB\$RELATION_NAME = '" . strtoupper($table_name) . "'
+							AND RDB\$UNIQUE_FLAG IS NULL
+							AND RDB\$FOREIGN_KEY IS NULL";
+					$col = 'index_name';
+				break;
+
+				case 'postgres':
+					$sql = "SELECT ic.relname as index_name
+						FROM pg_class bc, pg_class ic, pg_index i
+						WHERE (bc.oid = i.indrelid)
+							AND (ic.oid = i.indexrelid)
+							AND (bc.relname = '" . $table_name . "')
+							AND (i.indisunique != 't')
+							AND (i.indisprimary != 't')";
+					$col = 'index_name';
+				break;
+
+				case 'mysql_40':
+				case 'mysql_41':
+					$sql = 'SHOW KEYS
+						FROM ' . $table_name;
+					$col = 'Key_name';
+				break;
+
+				case 'oracle':
+					$sql = "SELECT index_name
+						FROM user_indexes
+						WHERE table_name = '" . strtoupper($table_name) . "'
+							AND generated = 'N'
+							AND uniqueness = 'NONUNIQUE'";
+					$col = 'index_name';
+				break;
+
+				case 'sqlite':
+					$sql = "PRAGMA index_info('" . $table_name . "');";
+					$col = 'name';
+				break;
+			}
+
+			$result = $this->db->sql_query($sql);
+			while ($row = $this->db->sql_fetchrow($result))
+			{
+				if (($this->sql_layer == 'mysql_40' || $this->sql_layer == 'mysql_41') && !$row['Non_unique'])
+				{
+					continue;
+				}
+
+				switch ($this->sql_layer)
+				{
+					case 'firebird':
+					case 'oracle':
+					case 'postgres':
+					case 'sqlite':
+						$row[$col] = substr($row[$col], strlen($table_name) + 1);
+					break;
+				}
+
+				$index_array[] = $row[$col];
+			}
+			$this->db->sql_freeresult($result);
+		}
+
+		return array_map('strtolower', $index_array);
+	}
+
+	/**
+	* Change column type (not name!)
+	*/
+	function sql_column_change($table_name, $column_name, $column_data, $inline = false)
+	{
+		$column_data = $this->sql_prepare_column_data($table_name, $column_name, $column_data);
+		$statements = array();
+
+		switch ($this->sql_layer)
+		{
+			case 'firebird':
+				// Change type...
+				if (!empty($column_data['column_type_sql_default']))
+				{
+					$statements[] = 'ALTER TABLE ' . $table_name . ' ALTER COLUMN "' . strtoupper($column_name) . '" TYPE ' . ' ' . $column_data['column_type_sql_type'];
+					$statements[] = 'ALTER TABLE ' . $table_name . ' ALTER COLUMN "' . strtoupper($column_name) . '" SET DEFAULT ' . ' ' . $column_data['column_type_sql_default'];
+				}
+				else
+				{
+					// TODO: try to change pkey without removing trigger, generator or constraints. ATM this query may fail.
+					$statements[] = 'ALTER TABLE ' . $table_name . ' ALTER COLUMN "' . strtoupper($column_name) . '" TYPE ' . ' ' . $column_data['column_type_sql_type'];
+				}
+			break;
+
+			case 'mssql':
+			case 'mssqlnative':
+				$statements[] = 'ALTER TABLE [' . $table_name . '] ALTER COLUMN [' . $column_name . '] ' . $column_data['column_type_sql'];
+
+				if (!empty($column_data['default']))
+				{
+					$sql = "SELECT CAST(SERVERPROPERTY('productversion') AS VARCHAR(25)) AS mssql_version";
+					$result = $this->db->sql_query($sql);
+					$row = $this->db->sql_fetchrow($result);
+					$this->db->sql_freeresult($result);
+
+					// Using TRANSACT-SQL for this statement because we do not want to have colliding data if statements are executed at a later stage
+					if ($row['mssql_version'][0] == '8')	// SQL Server 2000
+					{
+						$statements[] = "DECLARE @drop_default_name VARCHAR(100), @cmd VARCHAR(1000)
+							SET @drop_default_name =
+								(SELECT so.name FROM sysobjects so
+								JOIN sysconstraints sc ON so.id = sc.constid
+								WHERE object_name(so.parent_obj) = '{$table_name}'
+									AND so.xtype = 'D'
+									AND sc.colid = (SELECT colid FROM syscolumns
+										WHERE id = object_id('{$table_name}')
+											AND name = '{$column_name}'))
+							IF @drop_default_name <> ''
+							BEGIN
+								SET @cmd = 'ALTER TABLE [{$table_name}] DROP CONSTRAINT [' + @drop_default_name + ']'
+								EXEC(@cmd)
+							END
+							SET @cmd = 'ALTER TABLE [{$table_name}] ADD CONSTRAINT [DF_{$table_name}_{$column_name}_1] {$column_data['default']} FOR [{$column_name}]'
+							EXEC(@cmd)";
+					}
+					else
+					{
+						$statements[] = "DECLARE @drop_default_name VARCHAR(100), @cmd VARCHAR(1000)
+							SET @drop_default_name =
+								(SELECT dobj.name FROM sys.columns col 
+									LEFT OUTER JOIN sys.objects dobj ON (dobj.object_id = col.default_object_id AND dobj.type = 'D')
+								WHERE col.object_id = object_id('{$table_name}') 
+								AND col.name = '{$column_name}'
+								AND dobj.name IS NOT NULL)
+							IF @drop_default_name <> ''
+							BEGIN
+								SET @cmd = 'ALTER TABLE [{$table_name}] DROP CONSTRAINT [' + @drop_default_name + ']'
+								EXEC(@cmd)
+							END
+							SET @cmd = 'ALTER TABLE [{$table_name}] ADD CONSTRAINT [DF_{$table_name}_{$column_name}_1] {$column_data['default']} FOR [{$column_name}]'
+							EXEC(@cmd)";
+					}
+				}
+			break;
+
+			case 'mysql_40':
+			case 'mysql_41':
+				$statements[] = 'ALTER TABLE `' . $table_name . '` CHANGE `' . $column_name . '` `' . $column_name . '` ' . $column_data['column_type_sql'];
+			break;
+
+			case 'oracle':
+				$statements[] = 'ALTER TABLE ' . $table_name . ' MODIFY ' . $column_name . ' ' . $column_data['column_type_sql'];
+			break;
+
+			case 'postgres':
+				$sql = 'ALTER TABLE ' . $table_name . ' ';
+
+				$sql_array = array();
+				$sql_array[] = 'ALTER COLUMN ' . $column_name . ' TYPE ' . $column_data['column_type'];
+
+				if (isset($column_data['null']))
+				{
+					if ($column_data['null'] == 'NOT NULL')
+					{
+						$sql_array[] = 'ALTER COLUMN ' . $column_name . ' SET NOT NULL';
+					}
+					else if ($column_data['null'] == 'NULL')
+					{
+						$sql_array[] = 'ALTER COLUMN ' . $column_name . ' DROP NOT NULL';
+					}
+				}
+
+				if (isset($column_data['default']))
+				{
+					$sql_array[] = 'ALTER COLUMN ' . $column_name . ' SET DEFAULT ' . $column_data['default'];
+				}
+
+				// we don't want to double up on constraints if we change different number data types
+				if (isset($column_data['constraint']))
+				{
+					$constraint_sql = "SELECT consrc as constraint_data
+								FROM pg_constraint, pg_class bc
+								WHERE conrelid = bc.oid
+									AND bc.relname = '{$table_name}'
+									AND NOT EXISTS (
+										SELECT *
+											FROM pg_constraint as c, pg_inherits as i
+											WHERE i.inhrelid = pg_constraint.conrelid
+												AND c.conname = pg_constraint.conname
+												AND c.consrc = pg_constraint.consrc
+												AND c.conrelid = i.inhparent
+									)";
+
+					$constraint_exists = false;
+
+					$result = $this->db->sql_query($constraint_sql);
+					while ($row = $this->db->sql_fetchrow($result))
+					{
+						if (trim($row['constraint_data']) == trim($column_data['constraint']))
+						{
+							$constraint_exists = true;
+							break;
+						}
+					}
+					$this->db->sql_freeresult($result);
+
+					if (!$constraint_exists)
+					{
+						$sql_array[] = 'ADD ' . $column_data['constraint'];
+					}
+				}
+
+				$sql .= implode(', ', $sql_array);
+
+				$statements[] = $sql;
+			break;
+
+			case 'sqlite':
+
+				if ($inline && $this->return_statements)
+				{
+					return $column_name . ' ' . $column_data['column_type_sql'];
+				}
+
+				$sql = "SELECT sql
+					FROM sqlite_master
+					WHERE type = 'table'
+						AND name = '{$table_name}'
+					ORDER BY type DESC, name;";
+				$result = $this->db->sql_query($sql);
+
+				if (!$result)
+				{
+					break;
+				}
+
+				$row = $this->db->sql_fetchrow($result);
+				$this->db->sql_freeresult($result);
+
+				$statements[] = 'begin';
+
+				// Create a temp table and populate it, destroy the existing one
+				$statements[] = preg_replace('#CREATE\s+TABLE\s+"?' . $table_name . '"?#i', 'CREATE TEMPORARY TABLE ' . $table_name . '_temp', $row['sql']);
+				$statements[] = 'INSERT INTO ' . $table_name . '_temp SELECT * FROM ' . $table_name;
+				$statements[] = 'DROP TABLE ' . $table_name;
+
+				preg_match('#\((.*)\)#s', $row['sql'], $matches);
+
+				$new_table_cols = trim($matches[1]);
+				$old_table_cols = preg_split('/,(?![\s\w]+\))/m', $new_table_cols);
+				$column_list = array();
+
+				foreach ($old_table_cols as $key => $declaration)
+				{
+					$entities = preg_split('#\s+#', trim($declaration));
+					$column_list[] = $entities[0];
+					if ($entities[0] == $column_name)
+					{
+						$old_table_cols[$key] = $column_name . ' ' . $column_data['column_type_sql'];
+					}
+				}
+
+				$columns = implode(',', $column_list);
+
+				// create a new table and fill it up. destroy the temp one
+				$statements[] = 'CREATE TABLE ' . $table_name . ' (' . implode(',', $old_table_cols) . ');';
+				$statements[] = 'INSERT INTO ' . $table_name . ' (' . $columns . ') SELECT ' . $columns . ' FROM ' . $table_name . '_temp;';
+				$statements[] = 'DROP TABLE ' . $table_name . '_temp';
+
+				$statements[] = 'commit';
+
+			break;
+		}
+
+		return $this->_sql_run_sql($statements);
+	}
+}