A struggling white

触发器 在当前的表上,设置一个对每行数据的一个监听器,监听相关事件,每当事件触发时,就会执行一段由sql完成的一段功能代码触发事件： insert, delete, update new old : 针对的是触发的那张表 on 表名 insert ： 没有 old 有new 【对于插入，插入之前什么都...

触发器：create trigger Pj_trigger before update on pjxt_majorcourseinfo for each row begin declare zy varchar(20); set zy=old.ZYMC; if old.PJ=0 AND new.PJ=1 then insert into pjxt_o...

create trigger Pj_trigger before update on pjxt_majorcourseinfo foreach row beginDECLARE done INT DEFAULT 0;declare num varchar(20); – 用于记录每行的学号declare course_num varchar(20); – 用于记录课程编号 ...

第一种方法SELECT * from a where id = (SELECT max(id) FROM a);第二种方法： select * FROM 表名 ORDER BY id DESC LIMIT 0,1 ;

1、在进行排序之后进行序号：select (@i:=@i+1) as id,YX,ZY,ONE,TWO,THREE,FOUR,FIVE,SIX,SEVEN,EIGHT,NINE,TEN,SUM FROM ( select student.YX,student.ZY, sum(detail.ONE)/count() AS ONE,sum(detail.TWO)/count() AS TWO,su...