爲什麼我得到一個警告：觸發器編譯錯誤創建？

Question

這是我第一次使用SQL * Plus中的觸發器，並且我不想超過電影院顯示空間的最大容量。

放映時間給出max_occupancy。這是我有：

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

您可以只選擇這樣的語句：

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; 
/