为什么我会收到警告：触发器创建时出现编译错误？

Question

这是我第一次在 SQL*Plus 中使用 Triggers，而且我不想拥有超过电影院放映室的最大容量。

放映时间给出 max_occupancy。这是我的：

CREATE OR REPLACE TRIGGER over_capacity
BEFORE INSERT OR UPDATE ON tickets
FOR EACH ROW
WHEN (NEW.SHOWID=OLD.SHOWID)
DECLARE
    nope EXCEPTION;
    ti SYS_REFCURSOR;
    sh SYS_REFCURSOR;
    total INT;
    max_oc INT;
BEGIN
    OPEN sh FOR
         SELECT s.max_occupancy FROM showtimes s WHERE NEW.showid=s.showid;
    FETCH sh INTO max_oc;
    OPEN ti FOR
         SELECT COUNT(t.userid) FROM tickets t WHERE t.showid=NEW.showid;
    FETCH ti INTO total;
    IF total=max_oc THEN
       RAISE nope;
    END IF;
EXCEPTION
    WHEN nope THEN
    raise_application_error (-20500, 'AT CAPACITY');
END;
/

Answer 1

您可以只使用 select 语句，如下所示：

CREATE OR REPLACE TRIGGER over_capacity
BEFORE INSERT OR UPDATE ON tickets FOR EACH ROW
WHEN (NEW.SHOWID=OLD.SHOWID)
DECLARE
    nope EXCEPTION;
    total INT;
    max_oc INT;
BEGIN
    SELECT max_occupancy INTO total FROM showtimes WHERE showid = :new.showid;
    SELECT COUNT(userid) INTO max_oc FROM tickets WHERE showid=:new.showid;
    IF total=max_oc THEN
       RAISE nope;
    END IF;
EXCEPTION
    WHEN nope THEN
    raise_application_error (-20500, 'AT CAPACITY');
END;
/

为什么我会收到警告：触发器创建时出现编译错误？

Why am I getting a Warning: Trigger created with compilation errors?

triggers

sqlplus

oracle-sqldeveloper