-- mysql分组排序取前N条记录的最简洁的单条sql。
use test;
drop table if exists test;
create table test (
id int primary key,
cid int,
author varchar(30)
) engine=myisam;
insert into test values
(1,1,\'test1\'),
(2,1,\'test1\'),
(3,1,\'test2\'),
(4,1,\'test2\'),
(5,1,\'test2\'),
(6,1,\'test3\'),
(7,1,\'test3\'),
(8,1,\'test3\'),
(9,1,\'test3\'),
(10,2,\'test11\'),
(11,2,\'test11\'),
(12,2,\'test22\'),
(13,2,\'test22\'),
(14,2,\'test22\'),
(15,2,\'test33\'),
(16,2,\'test33\'),
(17,2,\'test33\'),
(18,2,\'test33\');
--
select * from (select cid,author,count(*) as number from test group by cid,author) a
where
2>(
select count(*)
from (select cid,author,count(*) as number from test group by cid,author) b
where a.cid=b.cid and a.number<b.number
)order by cid,number desc;