100分求助mysql

[weixin_36620557]

分数有5/10/15三种，每种分数都有若干条记录，
求助：
根据这三种分数，每种随机取10条记录
效果就是
15分的10条记录，10分的10条记录，5分的10条记录，求一条mysql语句

[Ginnnnnnnn]

给你个例子

create table tmp_tb
(
	id int auto_increment primary key,
    score int
);

insert into tmp_tb (score) values (5);
insert into tmp_tb (score) values (5);
insert into tmp_tb (score) values (10);
insert into tmp_tb (score) values (10);
insert into tmp_tb (score) values (15);
insert into tmp_tb (score) values (5);
insert into tmp_tb (score) values (5);
insert into tmp_tb (score) values (5);
insert into tmp_tb (score) values (15);
insert into tmp_tb (score) values (10);
insert into tmp_tb (score) values (15);
insert into tmp_tb (score) values (15);
insert into tmp_tb (score) values (10);
insert into tmp_tb (score) values (5);
insert into tmp_tb (score) values (5);
insert into tmp_tb (score) values (5);


delimiter //
set @i=0,
	@score=0;

select id,score from (
select *,@i:=if(@score=score,@i+1,1) as RNr,@score:=score as S
from (
select *
	from tmp_tb
    order by score,rand())a) a
    where RNr <=3
    ;
//
delimiter ;