CREATE OR REPLACE PROCEDURE Insert_Flight(passengerid IN int, airplaneid IN int, departuretime IN CHAR, arrivaltime IN CHAR, fromwhere IN CHAR, towhere IN CHAR)
  IS
  fid int;

  BEGIN
          SELECT MAX(flightid) INTO fid 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)
        );
        fid := fid + 1;

    IF (passengerid < 10 AND airplaneid < 10) THEN --Dung site 1
        INSERT INTO FLIGHT1 VALUES (fid, passengerid, airplaneid, TO_DATE(departuretime,'yyyy/mm/dd HH:MI:SS'),TO_DATE(arrivaltime,'yyyy/mm/dd HH:MI:SS'),fromwhere,towhere);
    ELSIF (passengerid < 10 AND airplaneid >= 10) THEN -- site 2
        INSERT INTO FLIGHT2@LINK_VUDB VALUES (fid, passengerid, airplaneid, TO_DATE(departuretime,'yyyy/mm/dd HH:MI:SS'),TO_DATE(arrivaltime,'yyyy/mm/dd HH:MI:SS'),fromwhere,towhere);
    ELSIF (passengerid >= 10 AND airplaneid < 10) THEN -- site 2
        INSERT INTO FLIGHT3@LINK_TRUNGDB VALUES (fid, passengerid, airplaneid, TO_DATE(departuretime,'yyyy/mm/dd HH:MI:SS'),TO_DATE(arrivaltime,'yyyy/mm/dd HH:MI:SS'),fromwhere,towhere);
    ELSIF (passengerid >= 10 AND airplaneid >= 10) THEN -- site 2
        INSERT INTO FLIGHT4@LINK_LONGDB VALUES (fid, passengerid, airplaneid, TO_DATE(departuretime,'yyyy/mm/dd HH:MI:SS'),TO_DATE(arrivaltime,'yyyy/mm/dd HH:MI:SS'),fromwhere,towhere);
    ELSE
        dbms_output.put_line('Error to insert');
    END IF;
  END;