在SQL Server中触发 - 获取为审计表完成的事务类型

Question

我正在写入触发器以将记录插入到我的Audit表中。

每当有在我的目标表中的数据发生变化时，触发将更新旧值，新值审计表

此外，还有所谓的Transaction和Transaction_Status

Transaction列列定义交易类型。可以是INSERT,UPDATE或DELETE。
Transaction_Status列表示SUCCESS或FAILURE

如何实现这一目标？

我的触发器：

Alter Trigger TR_test 
ON subscribers 
FOR UPDATE 
AS BEGIN 
DECLARE @OldValue xml,@NewValue xml, @changedby varchar(50), @ReferenceId int 
----------------------------------------------------------------------------- 
SELECT @OldValue=b.username, @NewValue=a.username, 
     @ReferenceId = a.user_id, @changedby = a.modified_by 
FROM inserted a, deleted b; 
----------------------------------------------------------------------------- 
INSERT INTO [dbo].[audit_log] 
      ([old_value],[new_value],[module],[reference_id],[transaction] 
      ,[transaction_status],[stack_trace],[modified_on],[modified_by]) 
    VALUES 
(@OldValue,@NewValue,'Subscriber',@ReferenceId,'_transaction', 
'_transaction_status','_stack_trace',getdate(),555) 

----------------------------------------------------------------------------- 
END 

Answer 1

一旦你解决您的触发涵盖所有三个操作，

IF EXISTS (SELECT 1 FROM inserted) 
BEGIN 
    IF EXISTS (SELECT 1 FROM deleted) 
    BEGIN 
    SET @action = 'UPDATE'; 
    END 
    ELSE 
    BEGIN 
    SET @action = 'INSERT'; 
    END 
ELSE 
BEGIN 
    SET @action = 'DELETE'; 
END 

另一个替代方案是三个独立的触发器，每一个动作。

如果您正在使用它，请谨慎使用MERGE ...或者在您迁移到SQL Server 2008或更高版本时做好准备。

编辑

我想你可能是后是INSTEAD OF触发，而不是（多么讽刺）。这是一个例子。让我们考虑一个非常简单的表与PK柱和独特的列：

CREATE TABLE dbo.foobar(id INT PRIMARY KEY, x CHAR(1) UNIQUE); 
GO 

和一个简单的日志表赶上活动：

CREATE TABLE dbo.myLog 
(
    foobar_id INT, 
    oldValue XML, 
    newValue XML, 
    [action] CHAR(6), 
    success BIT 
); 
GO 

以下INSTEAD OF触发器将拦截INSERT/UPDATE/DELETE命令，试图复制他们会做的工作，并记录它是否失败或成功：

CREATE TRIGGER dbo.foobar_inst 
ON dbo.foobar 
INSTEAD OF INSERT, UPDATE 
AS 
BEGIN 
    SET NOCOUNT ON; 

    DECLARE @action CHAR(6), @success BIT; 

    SELECT @action = 'DELETE', @success = 1; 

    IF EXISTS (SELECT 1 FROM inserted) 
    BEGIN 
    IF EXISTS (SELECT 1 FROM deleted) 
     SET @action = 'UPDATE'; 
    ELSE 
     SET @action = 'INSERT'; 
    END 

    BEGIN TRY 
    IF @action = 'INSERT' 
     INSERT dbo.foobar(id, x) SELECT id, x FROM inserted; 

    IF @action = 'UPDATE' 
     UPDATE f SET x = i.x FROM dbo.foobar AS f 
     INNER JOIN inserted AS i ON f.id = i.id; 

    IF @action = 'DELETE' 
     DELETE f FROM dbo.foobar AS f 
      INNER JOIN inserted AS i ON f.id = i.id; 
    END TRY 
    BEGIN CATCH 
    ROLLBACK; -- key part here! 

    SET @success = 0; 
    END CATCH 

    IF @action = 'INSERT' 
    INSERT dbo.myLog SELECT i.id, NULL, 
     (SELECT * FROM inserted WHERE id = i.id FOR XML PATH), 
     @action, @success FROM inserted AS i; 

    IF @action = 'UPDATE' 
    INSERT dbo.myLog SELECT i.id, 
     (SELECT * FROM deleted WHERE id = i.id FOR XML PATH), 
     (SELECT * FROM inserted WHERE id = i.id FOR XML PATH), 
     @action, @success FROM inserted AS i; 

    IF @action = 'DELETE' 
    INSERT dbo.myLog SELECT d.id, 
     (SELECT * FROM deleted WHERE id = d.id FOR XML PATH), 
     NULL, @action, @success FROM deleted AS d; 
END 
GO 

让我们试试一些非常简单的隐式交易上陈述：

-- these succeed: 

INSERT dbo.foobar SELECT 1, 'x'; 
GO 
INSERT dbo.foobar SELECT 2, 'y'; 
GO 

-- fails with PK violation: 

INSERT dbo.foobar SELECT 1, 'z'; 
GO 

-- fails with UQ violation: 

UPDATE dbo.foobar SET x = 'y' WHERE id = 1; 
GO 

检查日志：

SELECT foobar_id, oldValue, newValue, action, success FROM dbo.myLog; 

结果：

foobar_id oldValue      newValue      action success 
--------- ----------------------------- ----------------------------- ------ ------- 
1   NULL       <row><id>1</id><x>x</x></row> INSERT 1 
2   NULL       <row><id>2</id><x>y</x></row> INSERT 1 
1   NULL       <row><id>1</id><x>z</x></row> INSERT 0 
1   <row><id>1</id><x>x</x></row> <row><id>1</id><x>y</x></row> UPDATE 0 

当然，你可能希望在日志表等栏目，如用户，日期/时间，甚至可能是原来的说法。这并不意味着要成为全面的审计解决方案，只是一个例子。

正如Mikael指出的那样，这依赖于外部批处理是启动隐式事务的单个命令。如果外部批处理是明确的多语句事务，则必须测试该行为。

另请注意，在UPDATE影响零行的情况下，这不会捕获“失败”。因此，您需要明确定义“失败”的含义 - 在某些情况下，您可能需要在外部代码中构建自己的失败处理，而不是触发器。