如果仅指定 FOR 关键字，则 默认为AFTER触发器。
==========================================
--insert 触发器
create trigger tri_insert
on student
for insert
as
declare @student_id char(10)
select @student_id=s.student_id from
student s inner join inserted i
on s.student_id=i.student_id
if @student_id='0000000001'
begin
raiserror('不能插入1的学号!',16,8)
rollback tran
end
go ]
===============================================
--update触发器
create trigger tri_update
on student
for update
as
if update(student_id)
begin
raiserror('学号不能修改!',16,8)
rollback tran
end
go
==================================
--delete触发器
create trigger tri_delete
on student
for delete
as
declare @student_id varchar(10)
select @student_id=student_id from deleted
if @student_id='admin'
begin
raiserror('错误',16,8)
rollback tran
end