Question

在mysql中，order by查询的问题

在一张表中有学生的考试信息表中课程ID与课程表关联

课程有语文，数学，英语，

要求查询出每门课程的前三名（查询的是考试信息表）

我知道用select * from exam order by kechengID (但是每门课程的前三名

不知道怎么查询)

Answer 1

select t1.kechengID, t1.chengji
from exam as t1
join exam as t2 on t1.kechengID=t2.kechengID and t1.chengji<=t2.chengji
group by t1.kechengID, t1.chengji
having count(*)<=2;

先试一下，应该没问题

Answer 2

select * from exam where kechengID = '课程' order by kechengID limit 0,3;

Answer 3

select top（3） from exam order by kechengID？？？