事务

---事务:保障整个流程的完整执行，全部没有问题，统一提交，一旦有问题，回到原点。



begin tran --事务的开始

--开始写流程语句

--语句写完之后

if @@ERROR>0

begin

rollback tran--回滚事务

end

else

commit tran --提交事务









--级联删除套入事务中

alter trigger score_delete

on score

instead of delete

as

    declare @count int

    select @count=count(*)from deleted

    

    declare @i int

    set @i=0

    while @i<@count --循环遍历delete临时表的数据，然后转移到备份表中

    begin

    declare @sno varchar(20)

    declare @cno varchar(20)

    declare @degree decimal(4,1)

    select top 1 @sno=sno,@cno=cno,@degree=degree from deleted where 

    sno not in (select top (@i) sno from deleted)

    or cno not in(select top (@i) cno from deleted)

    

    --下面开始事务

    begin tran

    insert into scorebak values(@sno,@cno,@degree,getdate())

    delete from score where sno =@sno and @cno=@cno

    if @@error>0

    begin

    rollback tran

    end

    else

    commit tran

    

    

    set @i=@i+1

    end

go



delete from score where Sno=109

select*from scorebak

drop table scorebak