# a simple table with userid (id), setting (st) and value (vl):

CREATE TABLE `s` (
  `id` bigint(11) default NULL,
  `st` varchar(255) default NULL,
  `vl` varchar(255) default NULL,
  KEY `id` (`id`),
  KEY `st` (`st`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1


# I put in some random values:

SELECT * FROM s;

+------+------+------+
| id   | st   | vl   |
+------+------+------+
|    1 | a    | 15   |
|    1 | b    | 64   |
|    1 | c    | 75   |
|    2 | a    | 80   |
|    2 | b    | 78   |
|    2 | c    | 50   |
|    3 | a    | 17   |
|    3 | b    | 32   |
|    3 | c    | 12   |
|    4 | a    | 64   |
|    4 | b    | 81   |
|    4 | c    | 15   |
+------+------+------+
12 rows in set (0.00 sec)


# get the values we're looking for (our sort order):

SELECT id, vl AS vl2 FROM s WHERE st = 'c';

+------+------+
| id   | vl   |
+------+------+
|    1 | 75   |
|    2 | 50   |
|    3 | 12   |
|    4 | 15   |
+------+------+
4 rows in set (0.00 sec)


# join that to our original table and sort it:

SELECT s.* FROM s JOIN (SELECT id, vl AS vl2 FROM s WHERE st = 'c') s2 ON (s.id = s2.id) ORDER BY vl2 ASC, id ASC, st ASC;

+------+------+------+
| id   | st   | vl   |
+------+------+------+
|    3 | a    | 17   |
|    3 | b    | 32   |
|    3 | c    | 12   |
|    4 | a    | 64   |
|    4 | b    | 81   |
|    4 | c    | 15   |
|    2 | a    | 80   |
|    2 | b    | 78   |
|    2 | c    | 50   |
|    1 | a    | 15   |
|    1 | b    | 64   |
|    1 | c    | 75   |
+------+------+------+
12 rows in set (0.00 sec)