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1-- Example table (just an example. real table may contain hundreds of rows where field 2 is a duplicate but field 3 and 4 are different.)
2
3CREATE TABLE IF NOT EXISTS `docs` (
4  `field1` int(6) unsigned NOT NULL,
5  `field2` int(6) unsigned NOT NULL,
6  `field3` int(6) NOT NULL,
7  `field4` int(6) NOT NULL,
8  PRIMARY KEY (`field1`)
9) DEFAULT CHARSET=utf8;
10INSERT INTO `docs` (`field1`, `field2`, `field3`, `field4`) VALUES
11  ('27908', '82', '1', '17'),
12  ('27907', '82', '1', '50'),
13  ('402', '25', '1', '90'),
14  ('312', '25', '10', '8'); 
15     
16SELECT * FROM 
17(
18SELECT * FROM docs
19ORDER BY field2, field1 DESC
20) 
21     
22+--------+--------+--------+--------+
23| field1 | field2 | field3 | field4 |
24+--------+--------+--------+--------+
25|    402 |     25 |      1 |     90 |
26|    312 |     25 |     10 |      8 |
27|  27908 |     82 |      1 |     17 |
28|  27907 |     82 |      1 |     50 |
29+--------+--------+--------+--------+ 
30     
31SELECT * FROM 
32(
33SELECT * FROM docs
34ORDER BY field2, field1 DESC
35) temp
36GROUP BY field2 
37     
38+--------+--------+--------+--------+
39| field1 | field2 | field3 | field4 |
40+--------+--------+--------+--------+
41|    402 |     25 |      1 |     90 |
42|  27908 |     82 |      1 |     17 |
43+--------+--------+--------+--------+