在"INSTEAD OF UPDATE"触发器内部进行MSSQL条件检查

Question

使用MSSQL2008.

我有两张桌子.

TableResource
-------------
ID [bigint]
Attribute1 [int]
Attribute2 [int]
Attribute3 [int]
VersionId [uniqueidentifier]

和

TableResourceHistory
--------------------
ID [bigint]
Attribute3History [int]
HistoryDate [datetime]
VersionId [uniqueidentifier]

我有一个instead of update需要完成两件事的触发器:

• 如果字段" TableReResource.Attribute3"已更改,则使用"旧"Attribute3值将历史记录写入历史表,并且还修改表的" TableResource.VersionId"字段TableResource.
• 如果" TableReResource.Attribute3" 没有变化,那么只需通过UPDATE.

这是我到目前为止所做的,但是我无法想出相等比较来触发历史记录日志.

CREATE TRIGGER [dbo].[tr_UpdateResourceHistoryVersionId] ON [dbo].[TableResources]
INSTEAD OF UPDATE
AS
   SET NOCOUNT ON;
BEGIN                                           

-- ?? IF inserted.Attribute3 = deleted.Attribute3
-- ??  THEN we just pass the UPDATE through

UPDATE [TableResources]
SET 
    VersionId = inserted.VersionId,
    Attribute1 = inserted.Attribute1,
    Attribute2 = inserted.Attribute2        
FROM Inserted, TableResources
WHERE Inserted.ID = TableResources.ID

-- ??? ELSE, the Attribute3 field was updated, and we perform the history log
-- ??? and give it a new version number

-- History Log
INSERT TableResourceHistory (Attribute3History, HistoryDate, VersionId)
SELECT NEWID(), GETUTCDATE(), deleted.VersionId
FROM deleted    

-- pass through the update, but assign a new VersionId
UPDATE [TableResources]
  SET 
    VersionId = NEWID(),
    Attribute1 = inserted.Attribute1,
    Attribute2 = inserted.Attribute2        
FROM Inserted, TableResources
WHERE Inserted.ID = TableResources.ID   

END

有任何想法吗？TIA!

Answer 1

仅当 .history 表发生更改时才会发生历史表插入Attribute3。

尝试这个

CREATE TRIGGER [dbo].[tr_UpdateResourceHistoryVersionId]
ON [dbo].[TableResources]
INSTEAD OF UPDATE
AS
    SET NOCOUNT ON;

  BEGIN

      IF EXISTS(SELECT 1
                FROM   inserted i
                       JOIN deleted d
                         ON i.ID = d.ID
                            AND i.Attribute3 = d.Attribute3)
        BEGIN
            UPDATE T
            SET    VersionId = inserted.VersionId,
                   Attribute1 = inserted.Attribute1,
                   Attribute2 = inserted.Attribute2
            FROM   Inserted I
                   JOIN [TableResources] T
                     ON I.ID = T.ID
                   JOIN deleted d
                     ON i.ID = d.ID
                        AND i.Attribute3 = d.Attribute3
        END

      IF EXISTS(SELECT 1
                FROM   inserted i
                       JOIN deleted d
                         ON i.ID = d.ID
                            AND i.Attribute3 <> d.Attribute3)
        BEGIN
            INSERT TableResourceHistory
                   (Attribute3History,HistoryDate,VersionId)
            SELECT Newid(),
                   Getutcdate(),
                   d.VersionId
            FROM   deleted d
                   JOIN Inserted i
                     ON i.ID = d.ID
                        AND i.Attribute3 <> d.Attribute3

            -- pass through the update, but assign a new VersionId
            UPDATE T
            SET    VersionId = Newid(),
                   Attribute1 = inserted.Attribute1,
                   Attribute2 = inserted.Attribute2
            FROM   Inserted I
                   JOIN [TableResources] T
                     ON I.ID = T.ID
                   JOIN deleted d
                     ON i.ID = d.ID
                        AND i.Attribute3 <> d.Attribute3
        END
  END 

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