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  • SQL Sever 第五堂课:触发器知识。

    --触发器:触发器就是一种特殊的存储过程
    --特殊的地方在于,触发器是通过对数据库表的操作,来引发
    --存储过程是通过人为exec来执行
    
    
    select *from student
    create trigger Student_Insert --创建触发器
    on student  --指定触发器所在的表
    after insert --当执行insert操作的时候自动执行触发器,for 和after都是在操作后执行
    as
        update student set sbirthdy='1999-9-9' where sno=1
    go
    insert into student values(7,'向立硕','','1989-2-22',95031)
    
    
    
    create trigger Student_Delete
    on student
    instead of delete --替换某个操作,用触发器的过程来替换删除的操作,不再能够删除stduent表数据
    as
        update student set sbirthdy = '2015-4-29' where sno = 2
    go
    delete from student
    select*from student
    drop trigger student_delete
    
    
    
    
    -----------------------------触发器格式
    create trigger 触发器名
    on 表名
    ((for/after)|instead of) 动作(insert|update|delete)
    as
        存储过程内容
    go
    
    
    for/after :先执行操作,再执行触发器
    instead of:直接替换操作
    --
    create trigger Student_delete2
    on student
    instead of delete   --把delete from student 这个操作直接替换掉
    as
        delete from score where sno = 2
        delete from student where sno = 2   --有主外键关系可以执行两个表
    go
    delete from student 
    drop trigger student_delete2--删除触发器
    select*from student
    select*from score
    
    
    --触发器中的临时表:deleted,inserted
    delete from course where cno='3-245'
    
    create trigger Course_Delete   --创建一个的存储过程
    on course                --在课程表里
    instead of delete      --直接替换delete操作
    as
        select *from deleted  --这是一个临时表。替换掉操作后,里面存着你要删除的那些数据
    go
    delete from course where cno='3-245'
    --deleted是一个临时表,里面存着你要删除的那些数据、
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  • 原文地址:https://www.cnblogs.com/275147378abc/p/4465638.html
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