如何解决Oracle在触发器中不允许子查询的限制。
这是我尝试创建的示例触发器,但我无法使用,因为我无法使用子查询。
CREATE OR REPLACE TRIGGER trigger_w_subquery
AFTER UPDATE OR INSERT ON project_archiving
FOR EACH ROW WHEN (old.archiving_status <> new.archiving_status
AND new.archiving_status = 1
AND (SELECT offer FROM projects WHERE projnum = :new.projnum) IS NULL
)
BEGIN
INSERT INTO offer_log (offer, status, date)
VALUES (null, 9, sysdate);
END;
答案 0 :(得分:9)
此触发器可以执行此操作:
CREATE OR REPLACE TRIGGER trigger_w_subquery
AFTER UPDATE OR INSERT ON project_archiving
FOR EACH ROW WHEN (old.archiving_status <> new.archiving_status
AND new.archiving_status = 1
)
DECLARE
l_offer projects.offer%TYPE;
BEGIN
SELECT offer INTO l_offer
FROM projects
WHERE projnum = :new.projnum;
IF l_offer IS NULL THEN
INSERT INTO offer_log (offer, status, date)
VALUES (null, 9, sysdate);
END IF;
END;
我假设项目中的选择总是会找到一行;如果不是,它将引发您可能需要处理的NO_DATA_FOUND异常。
答案 1 :(得分:5)
我希望你想要像
这样的东西CREATE OR REPLACE TRIGGER trigger_w_subquery
AFTER UPDATE OR INSERT ON project_archiving
FOR EACH ROW
WHEN (old.archiving_status <> new.archiving_status
AND new.archiving_status = 1)
DECLARE
l_offer projects.offer%TYPE;
BEGIN
SELECT offer
INTO l_offer
FROM projects
WHERE projnum = :new.projnum;
IF( l_offer IS NULL )
THEN
INSERT INTO offer_log (offer, status, date)
VALUES (null, 9, sysdate);
END IF;
END;
答案 2 :(得分:2)
你可以把条件放在行动中(在BEGIN和END之间)而不是'是否会发射'吗?是的,这意味着触发器主体可能会更频繁地被触发 - 但是如果它能解决你的问题......