sql server触发器的简单例子

--//sql server触发器的例子
CREATE TRIGGER qf_trigger
   ON  User_table
   for INSERT,DELETE,UPDATE
AS
BEGIN
    declare @userid varchar(20)

    --保存旧值
    declare rs cursor for
        select userid from deleted
    open rs
    fetch next from rs into @userid
    while @@fetch_status=0
    begin
        if update(用户名)
            insert into old_users(userid) values (@userid)
        fetch next from rs into @userid
    end
    close rs
    deallocate rs

    --保存新值
    declare rs cursor for
        select userid from inserted
    open rs
    fetch next from rs into @userid
    while @@fetch_status=0
    begin
        if update(用户名)
        begin
            if(@userid='admin')
            begin
                raiserror('此用户名禁用!',10,1) with nowait
                rollback
                return
            end
            insert into new_users(userid) values (@userid)
        end
        fetch next from rs into @userid
    end
    close rs
    deallocate rs
END