mysql分組排序取前N條記錄的最簡潔的單條sql !

-- mysql分組排序取前N條記錄的最簡潔的單條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;