Question

我有两张表person和customer。从person中删除时，我要从customer删除

CREATE TRIGGER DELCUS
ON Person
AFTER DELETE
FOR EACH ROW
begin
DELETE FROM customer
WHERE customer.PersonID_Fk=Person.PersonId;
end

这是我得到的错误：

Msg 156, Level 15, State 1, Procedure DELCUS, Line 5
Incorrect syntax near the keyword 'FOR'.

为什么不能读取每一行？

Answer 1

如果您使用的是SQL Server，则需要：

CREATE TRIGGER DELCUS
ON Person
AFTER DELETE AS
begin
DELETE c 
FROM customer
WHERE EXISTS (select 1 from deleted where customer.PersonID_Fk=deleted.PersonId);
end

如果您使用的是MySQL，那就是：

CREATE TRIGGER DELCUS
ON Person
AFTER DELETE AS
begin
DELETE c 
FROM customer
WHERE EXISTS (select 1 from old where customer.PersonID_Fk=old.PersonId);
end

但实际上，如果您确实设置了FK，那么当您尝试删除某个人的参考失败时，它会出错。最好的办法是将你的FK设置为on delete cascade。

Answer 2

或者您可以使用：

DELETE FROM customer
WHERE customer.PersonID_Fk in (select personid from deleted)

为什么我会在关键字'FOR'附近找到“语法不正确”？

2 个答案: