BEGIN
  DECLARE dest INT;
  SET dest =0;
  SELECT id
    INTO dest
    FROM Destinations
    WHERE id = number;
  WHILE (dest=0 AND length(number) > 0) DO
    SET number = substring(number,1, length(number)-1);
    SELECT id
      INTO dest
      FROM Destinations
      WHERE id = number;
  END WHILE;
  return dest;
END