/**
  * Returns the error text from the last operation done on the database server.
  * @param resource $connection (optional)	The database server connection, for detailed description see the method query().
  * @return string							Returns the error text from the last database operation, or '' (empty string) if no error occurred.
  */
 public static function error($connection = null)
 {
     return self::use_default_connection($connection) ? mysqli::mysqli_error() : mysqli::mysqli_error($connection);
 }