Question

我想编写一个触发器，该触发器应该查找插入或更新的值是否为正，并将其替换为负值。我试过这段代码：

create trigger trigger_after_updaten on Inbox
AFTER Update 
AS
begin
DECLARE @t INT 
If ((SELECT @t=ID_In FROM updated)>0) 
UPDATE Inbox SET t=@t*-1
END

但是它显示了这个错误：

Msg 102, Level 15, State 1, Procedure trigger_after_updaten, Line 223
Incorrect syntax near '='.

如何以正确的方式做到这一点？

Answer 1

这适合您的触发器：

CREATE TRIGGER trigger_after_updaten on Inbox
AFTER UPDATE 
AS
BEGIN
    UPDATE Inbox SET t = CASE WHEN(inserted.t < 0) THEN inserted.t ELSE -inserted.t END
    FROM inserted
    INNER JOIN Inbox 
        ON inserted.KEY_FIELD = Inbox.KEY_FIELD
END

如何在更新或插入后将正插入值转换为负值？

1 个答案: