Code Changes

	/**
	* @var object DB object
	*/
	var $db = NULL;

	/**
	* The Column types for every database we support
	* @var 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(

	* Constructor. Set DB Object and set {@link $return_statements return_statements}.
	*
	* @param phpbb_dbal	$db					DBAL object
	* @param bool		$return_statements	True if only statements should be returned and no SQL being executed

		$this->return_statements = $return_statements;

			break;

			case 'mssqlnative':
				$this->sql_layer = 'mssqlnative';

	}

	/**
	* 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);

		$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);
				}
			}
		}

						else
						{
							$sqlite_data[$table]['add_columns'][] = $result;
						}
					}
					else if ($this->return_statements)
					{
						$statements = array_merge($statements, $result);

					if (!$this->sql_index_exists($table, $index_name))
					{
						continue;
					}

						}

					if ($this->sql_unique_index_exists($table, $index_name))
					{
						continue;
					}

					if ($this->sql_index_exists($table, $index_name))
					{
						continue;
					}

			}
		}

		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';

		$columns = array();

			case 'mssqlnative':

			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}'";

				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);

					}

		}

		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';

					}

		}

		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';

		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;
			}

					else if (strpos($row[$col], strtoupper($table_name)) === 0)
					{
						$row[$col] = substr($row[$col], strlen($table_name) + 1);
					}
				break;

				$this->db->sql_freeresult($result);

		$this->db->sql_freeresult($result);

		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);
		}

				$return_array['column_type_sql_type'] = " {$column_type} ";

					$return_array['column_type_sql_default'] = ((is_numeric($column_data[1])) ? $column_data[1] : "'{$column_data[1]}'") . ' ';

				}

				$return_array['auto_increment'] = false;
				if (isset($column_data[2]) && $column_data[2] == 'auto_increment')
				{
					$return_array['auto_increment'] = true;

			case 'mssqlnative':

				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]';

				$return_array['auto_increment'] = false;
				if (isset($column_data[2]) && $column_data[2] == 'auto_increment')
				{
					$return_array['auto_increment'] = true;
				}

				$return_array['auto_increment'] = false;

					$return_array['auto_increment'] = true;

				$return_array['primary_key_set'] = false;

					$return_array['primary_key_set'] = true;

			case 'mssqlnative':
				// Does not support AFTER, only through temporary table

				// Does not support AFTER, only through temporary table

				// Does not support AFTER, only through temporary table
				if (version_compare($this->db->sql_server_info(true), '8.0', '>='))
				{

				}
				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'];
					}
				}

				if ($inline && $this->return_statements)
				{
					return $column_name . ' ' . $column_data['column_type_sql'];
				}

			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'] . ']';
					}
				}

				if ($inline && $this->return_statements)
				{
					return $column_name;
				}

			case 'mssqlnative':

			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);

			case 'mysql_40':
			case 'mysql_41':

			case 'mssqlnative':

				if ($inline && $this->return_statements)
				{
					return $column;
				}

		$table_prefix = substr(CONFIG_TABLE, 0, -6); // strlen(config)
		if (strlen($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);
		}

		$table_prefix = substr(CONFIG_TABLE, 0, -6); // strlen(config)
		if (strlen($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);
		}

				// 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 'mssqlnative':

				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)";
					}
				}

				if ($inline && $this->return_statements)
				{
					return $column_name . ' ' . $column_data['column_type_sql'];
				}