CREATE OR REPLACE PROCEDURE Update_Flight(
  fid IN CHAR,
  passengerid IN int,
  airplaneid IN int,
  departuretime IN CHAR,
  arrivaltime IN CHAR,
  from_where IN CHAR,
  to_where IN CHAR)
  IS
  countid CHAR;
  BEGIN
    SELECT flightid INTO countid FROM (
      (SELECT flightid FROM FLIGHT1)
        UNION ALL
      (SELECT flightid FROM FLIGHT2@LINK_VUDB)
        UNION ALL
      (SELECT flightid FROM FLIGHT3@LINK_TRUNGDB)
        UNION ALL
      (SELECT flightid FROM FLIGHT4@LINK_LONGDB)
    ) WHERE passenger_id = passengerid AND airplane_id = airplaneid;
    IF (passengerid < 10 AND airplaneid <10 ) THEN --site 1
    BEGIN
      UPDATE FLIGHT1
      SET departure_time = TO_DATE(departuretime,'yyyy/mm/dd HH:MI:SS'),
      arrival_time = TO_DATE(arrivaltime,'yyyy/mm/dd HH:MI:SS'),
      fromwhere = from_where,
      towhere=to_where
      WHERE flightid = countid;
    END;
    ELSIF (passengerid < 10 AND airplaneid >= 10) THEN -- site 2
    BEGIN
      UPDATE FLIGHT2@LINK_VUDB
      SET departure_time = TO_DATE(departuretime,'yyyy/mm/dd HH:MI:SS'),
      arrival_time = TO_DATE(arrivaltime,'yyyy/mm/dd HH:MI:SS'),
      fromwhere = from_where,
      towhere=to_where
      WHERE flightid = countid;
    END;
    ELSIF (passengerid >= 10 AND airplaneid <10) THEN --site 3
    BEGIN
      UPDATE FLIGHT3@LINK_TRUNGDB
      SET departure_time = TO_DATE(departuretime,'yyyy/mm/dd HH:MI:SS'),
      arrival_time = TO_DATE(arrivaltime,'yyyy/mm/dd HH:MI:SS'),
      fromwhere = from_where,
      towhere=to_where
      WHERE flightid = countid;
    END;
    ELSIF (passengerid >= 10 AND airplaneid >= 10) THEN --site 4
    BEGIN
      UPDATE FLIGHT4@LINK_LONGDB
      SET departure_time = TO_DATE(departuretime,'yyyy/mm/dd HH:MI:SS'),
      arrival_time = TO_DATE(arrivaltime,'yyyy/mm/dd HH:MI:SS'),
      fromwhere = from_where,
      towhere=to_where
      WHERE flightid = countid;
    END;
    END IF;
  END;