数据库课件

/*删除类触发器*/ /*当删除student记录时，自动删除grade中的相关记录*/ create trigger st_del_trigger on student for delete as delete grade from grade a,deleted b where a.sno=b.sno /*插入类触发器*/ /*当插入sc记录时，检查student中是否存在相应的学号*/ create trigger sc_ins_trigger on sc for insert as if(select count(*) from student a,inserted b where a.sno=b.sno)=0 begin print '非法学号' rollback transaction end