说明

触发器是一种特殊的存储过程，它不能被显式地调用，而是在往表中插入记录﹑更新记录或者删除记录时被自动地激活。 所以触发器可以用来实现对表实施复杂的完整性约束。

分类使用

“Instead of”触发器在执行真正“插入”之前被执行。除表之外，“Instead of” 触发器也可以用于视图，用来扩展视图可以支持的更新操作。
使用：INSTEAD OF INSERT

“After”触发器在Insert、Update或Deleted语句执行之后被触发。“After”触发器只能用于表。
使用：AFTER INSERT

示例(after)

insert触发器

drop trigger [dbo].[Trigger_Insert_Test]
--不能插入临时表
CREATE TABLE sal_order_test
			(FID INT IDENTITY (1,1),
			 FBILLNO VARCHAR(20) NOT NULL DEFAULT(''),
			 FDATE VARCHAR(20) NOT NULL DEFAULT('')
			)
CREATE TABLE sal_order_testLog
			(FID INT IDENTITY (1,1),
			 Direction VARCHAR(2000) NOT NULL DEFAULT(''),
			 FDATE VARCHAR(200)  NOT NULL DEFAULT('')
			)
drop TABLE sal_order_testLog 
drop TABLE sal_order_test 
select *from sal_order_testLog
select *from sal_order_test

--Insert 触发器
Create TRIGGER [dbo].[Trigger_Insert_Test]
   ON  [dbo].[T_SAL_ORDER]
   AFTER INSERT
AS 
BEGIN
	
	SET NOCOUNT ON;

	Declare @fid int;
	Select @fid=FID  From inserted
	Declare @fbillno varchar(2000);
	Select @fbillno=FBILLNO  From inserted

	if ( (select COUNT(*) from sal_order_test where FBILLNO = @fbillno)=0)
		Begin
			Insert into sal_order_test(  FBILLNO, FDATE)
			Select  FBILLNO, FDATE From inserted
			
		    insert into sal_order_testLog(Direction,Fdate) values( @fbillno+'执行成功',convert(varchar,getdate(),21))
		End
	ELSE
		Begin
		    insert into sal_order_testLog(Direction,Fdate) values( @fbillno+'执行失败',convert(varchar,getdate(),21))
			--rollback transaction     --数据回滚
		END
    
END

update 触发器

--UPDATE 触发器
Create TRIGGER [dbo].[Trigger_UPDATE_Test]
   ON  [dbo].[T_SAL_ORDER]
   AFTER UPDATE
AS 
BEGIN
	
	SET NOCOUNT ON;
	
	--写自己要执行的操作，这里只是记录一下日志
    Insert Into sal_order_testLog( Direction, FDATE)
	Select  FBILLNO+'更新成功！',  GETDATE() From deleted
    
END

delete触发器

--Delete 触发器
Create TRIGGER [dbo].[Trigger_Delete_Test]
   ON  [dbo].[T_SAL_ORDER]
   AFTER DELETE
AS 
BEGIN
	SET NOCOUNT ON;

    Insert Into sal_order_testLog( Direction, FDATE)
	Select  FBILLNO+'删除成功！',  GETDATE() From deleted

END