public static function drop_index($table, $index_name, $db = null)
	{
		if (strtoupper($index_name) == 'PRIMARY')
		{
			$sql = 'ALTER TABLE '.\DB::quote_identifier(\DB::table_prefix($table, $db ? $db : static::$connection), $db ? $db : static::$connection);
			$sql .= ' DROP PRIMARY KEY';
		}
		else
		{
			$sql = 'DROP INDEX '.\DB::quote_identifier($index_name, $db ? $db : static::$connection);
			$sql .= ' ON '.\DB::quote_identifier(\DB::table_prefix($table, $db ? $db : static::$connection), $db ? $db : static::$connection);
		}

		return \DB::query($sql, \DB::UPDATE)->execute($db ? $db : static::$connection);
	}