Question

我尝试编写一个触发器，在允许某个人在乘客名单上预订之前检查以确保满足条件。但是当条件不满足时，我想禁止插入乘客名单。我的触发器触发，但插入发生在任何地方。我该如何解决这个问题？我做错了什么？

例如，

INSERT INTO  passengerlist_my (flightID, personID, seatnumber)
    VALUES (1, 5, '43B');

上述插入语句在不满足条件时执行。 personID 5的人已被预订。但是当我运行insert语句时，它仍会插入

SET serveroutput ON
    /
    CREATE OR REPLACE TRIGGER bookpersons
    BEFORE INSERT ON  passengerlist_my
    FOR EACH ROW
    DECLARE
       --declaration section
       checkflight number;
       bookedseats number;
       planecapacity number;
       chkpbooked number;

       FLIGHT_IS_FULL EXCEPTION;
       PERSON_IS_BOOKED EXCEPTION;
       querystr VARCHAR2(255) := 'INSERT INTO  passengerlist_my (flightID, personID, seatnumber)
                                    VALUES (:NEW.flightID, :NEW.personID, :NEW.seatnumber)';

    BEGIN
        --check IF FLIGHT exists
        SELECT COUNT(*) INTO checkflight FROM FLIGHT WHERE flightID = :NEW.flightID;
        IF checkflight<1 THEN
            RAISE_APPLICATION_ERROR(-2000, 'Flight doesnt Exist');
        END IF;   

        --check booked seats
        SELECT COUNT(*) INTO bookedseats FROM  passengerlist WHERE flightID = :NEW.flightID;

        --check plane capacity
        SELECT NUMBEROFSEATS INTO planecapacity FROM PLANETYPE
        JOIN PLANE USING (PLANETYPEID)
        JOIN FLIGHT USING (PLANEID)
        WHERE flightID = :NEW.flightID;

        --check if person is already booked
        SELECT COUNT(*) INTO chkpbooked 
        FROM PASSENGERLIST_MY 
        WHERE FLIGHTID = :NEW.flightID AND personID = :NEW.personID;
        IF chkpbooked>=1 THEN
            RAISE PERSON_IS_BOOKED;
        END IF;

        IF bookedseats>=planecapacity THEN
            RAISE FLIGHT_IS_FULL;
        END IF;

        INSERT INTO  passengerlist_my (flightID, personID, seatnumber)
        VALUES (:NEW.flightID, :NEW.personID, :NEW.seatnumber);
        COMMIT;


    EXCEPTION
        WHEN FLIGHT_IS_FULL THEN
        DBMS_OUTPUT.PUT_LINE('This flight is FULL. Passenger cannot be booked!');
        WHEN PERSON_IS_BOOKED THEN
            DBMS_OUTPUT.PUT_LINE('Person is already booked!');
        WHEN OTHERS THEN
        DBMS_OUTPUT.PUT_LINE('Error Occured. Passenger cannot be booked!');
    END;
    /

Answer 1

问题是你的异常处理程序正在吃异常而不是重新提升它们。尝试将异常处理程序更改为：

EXCEPTION
    WHEN FLIGHT_IS_FULL THEN
      DBMS_OUTPUT.PUT_LINE('This flight is FULL. Passenger cannot be booked!');
      RAISE;

    WHEN PERSON_IS_BOOKED THEN
      DBMS_OUTPUT.PUT_LINE('Person is already booked!');
      RAISE;

    WHEN OTHERS THEN
      DBMS_OUTPUT.PUT_LINE('Error Occured. Passenger cannot be booked!');
      RAISE;

这将导致异常重新引发到调用代码中的任何现有处理程序，该处理程序应该足够智能以回滚事务。

分享并享受。

插入触发器之前的PL / SQL没有停止插入

1 个答案: