查询每类最大的两个值的SQL要怎么写啊~~

[afeiqiang]

比如这样的场景：表 exam 记录学生每次测验的成绩，stu_id 是学生id，score 是成绩。查询出全部学生的最好的两次测验成绩的sql要怎么写？
比如表 exam 的数据如下，

1 98
1 96
2 100
1 85
2 89
2 90
3 82
3 66
3 75

查询到结果应该是
1 98
1 96
2 100
2 90
3 82
3 75

[小小小小蜗牛]

不来这么复杂啦 会晕的
select id, max(score) from exam
group by id
having count(id)=2
limit 2; 这个不错

[wwwwb]

SELECT * from tty a where 2>(select count(*) from tty where a.id=id and a.score<score)

[Rotel-刘志东]

select id, max(score) from exam
group by id
having count(id)=2
limit 2;

[ACMAIN_CHM]

参考下贴中的多种方法

http://blog.csdn.net/acmain_chm/article/details/4126306
[征集]分组取最大N条记录方法征集，及散分....

[Rotel-刘志东]

select *
from Table1 a
where id in (select id from Table1 where ClsNo=a.ClsNo order by Score desc limit 2)
order by a.ClsNo,a.Score desc

[Rotel-刘志东]

select *
from exam a
where id in (select id from exam where ClsNo=a.ClsNo order by Score desc limit 2)
order by a.ClsNo,a.Score desc

[afeiqiang]

[Quote=引用 1 楼 的回复:]
SELECT * from tty a where 2>(select count(*) from tty where a.id=id and a.score<score)
[/Quote]
琢磨了很久，终于弄明白了

[afeiqiang]

[Quote=引用 3 楼 的回复:]

参考下贴中的多种方法

http://blog.csdn.net/acmain_chm/article/details/4126306
[征集]分组取最大N条记录方法征集，及散分....
[/Quote]

这个很好，谢谢

[afeiqiang]

[Quote=引用 5 楼 的回复:]

select *
from exam a
where id in (select id from exam where ClsNo=a.ClsNo order by Score desc limit 2)
order by a.ClsNo,a.Score desc
[/Quote]

上面几条亲测全通不过，不过还是谢谢