Question

作为一个经验很少或没有经验的用户，我必须在桌面上创建一个触发器（或找到另一个解决方案）。需要完成的是，当列ESB的值在表中的另一行中更改为“1”时，该列必须设置为“0”。

我的目的是使用AFTER UPDATE触发器来执行此操作。

ALTER TRIGGER [TR_PHOTO_UPD]
   ON    [SOA].[dbo].[photos_TEST]
   AFTER  UPDATE
AS 

DECLARE @ID  VARCHAR(10)
DECLARE @ESB  VARCHAR(1)

SELECT @ID  = (SELECT TOP(1) ID 
      FROM SOA.dbo.photos_TEST 
               WHERE esb = 'Q' 
               ORDER BY ARRIVALDATETIME ASC)
SELECT @ESB (SELECT esb FROM INSERTED)


IF @ESB = '1'
UPDATE SOA.dbo.photos_TEST SET esb = '0' WHERE ID = @I

您可能理解，这不起作用，也不适用于下一个触发器定义。

ALTER TRIGGER [TR_PHOTO_UPD]
   ON    [SOA].[dbo].[photos_TEST]
   AFTER  UPDATE
AS 

DECLARE @ID  VARCHAR(10)
DECLARE @ESB  VARCHAR(1)

SELECT @ID  = (SELECT TOP(1) ID 
      FROM SOA.dbo.photos_TEST 
               WHERE esb = 'Q' 
               ORDER BY ARRIVALDATETIME ASC)
SELECT @ESB (SELECT esb FROM INSERTED)


    IF @ESB = '1'
    BEGIN
  UPDATE SOA.dbo.photos_TEST 
  SET esb = '0'
  WHERE id = (SELECT TOP(1) ID 
       FROM SOA.dbo.photos_TEST 
       WHERE esb = 'Q' 
       ORDER BY ARRIVALDATETIME ASC)
    END

经过几个小时的谷歌搜索并尝试我还没有找到为什么行没有更新为'0'。我怀疑AFTER UPDATE触发器中的UPDATE是它无法工作的原因。有人提出任何提示或更好的解决方案吗？

干杯，

彼得

Answer 1

在处理多个更新时，这两种方法都不起作用。

为什么你甚至需要根据具体情况来做。你无论如何都不能在桌子上运行更新。

可能有以下几点：

If Update(ESB)
    begin

       Update a
       Set AnotherColumn = 0
       From YourTable a
       Join inserted ins on a.Id = ins.Id
       Where ins.ESB = 1

    end

这将检查它是否是已更新的ESB列。如果是，那么它运行update语句将AnotherColumn设置为零，其中ESB值为1

我认为这应该对你有用

Answer 2

感谢Barry的帮助，如果确定了触发器的话;

    CREATE TRIGGER TR_PHOTO_AU
   ON          SOA.dbo.photos
   AFTER     UPDATE
AS 

DECLARE @MAXCONC INT  -- Maximum concurrent processes
DECLARE @CONC INT     -- Actual concurrent processes

SET @MAXCONC = 1      -- 1 concurrent process

-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON

-- If column esb is involved in the update, does not necessarily mean
-- that the column itself is updated
If ( Update(ESB) )
BEGIN
    -- If column esb has been changed to 1
    IF ((SELECT esb FROM INSERTED) = '1')
    BEGIN
        -- count the number of (imminent) active processes
        SET @CONC = (SELECT COUNT(*) 
                  FROM SOA.dbo.photos pc
                  WHERE pc.esb in ('0','R'))

        -- if maximum has not been reached
        IF NOT ( @CONC >= @MAXCONC )
        BEGIN
            -- set additional rows esb to '0' to match @MAXCONC
               UPDATE TOP(@MAXCONC-@CONC) p2
               SET p2.esb = '0'
            FROM ( SELECT TOP(@MAXCONC-@CONC) p1.esb 
                   FROM SOA.dbo.photos  p1
                   WHERE  p1.esb = 'Q'
                   ORDER BY p1.arrivaldatetime ASC 

            ) p2

        END
    END
END

MS SQL 2005 AFTER UPDATE触发器更新除更新之外的其他行

2 个答案: