--MySQL group sorting takes the simplest single SQL of the first N records.
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');
INSERT INTO test VALUES (200,200, '200test_nagios');
SELECT * FROM (SELECT cid,author,COUNT(*) AS number FROM test GROUP BY cid,author) a WHERE N >( 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;
The results are as follows:
mysql> SELECT * FROM (SELECT cid,author,COUNT(*) AS number FROM test GROUP BY cid,author) a -> WHERE -> 3>( -> 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; +------+----------------+--------+ | cid | author | number | +------+----------------+--------+ | 1 | test3 | 4 | | 1 | test2 | 3 | | 1 | test1 | 2 | | 2 | test33 | 4 | | 2 | test22 | 3 | | 2 | test11 | 2 | | 200 | 200test_nagios | 1 | +------+----------------+--------+ 7 rows in set (0.00 sec)
##N is to take the first few judgments after grouping, N=3 is to take the first 3
##--Generate automatic number sequenceSET @ROW=0;
SELECT a.*,(@ROW:=@ROW +1)Rank
FROM test a;