mysql> EXPLAIN SELECT * FROM clientfile c1 JOIN casino_clientfile c2 USING(clientfile_id) LEFT JOIN clientfile_pool c3 ON(-c2.casino_id=c3.clientfile_pool_id) LEFT JOIN casino_clientfile_pool c4 USING(clientfile_pool_id) WHERE (file_type IN('WIN32', 'LobbyComponent', 'LobbyInclude', 'LobbyThumbnail')) AND (c4.casino_id=79 OR clientfile_pool_id=0 OR c2.casino_id=79) ORDER BY CASE WHEN c2.casino_id>0 THEN c2.casino_id ELSE NULL END DESC,c2.casino_id ASC;
+----+-------------+-------+--------+---------------------------------+--------------------+---------+-----------------------------------+------+----------------------------------------------+
| id | select_type | table | type   | possible_keys                   | key                | key_len | ref                               | rows | Extra                                        |
+----+-------------+-------+--------+---------------------------------+--------------------+---------+-----------------------------------+------+----------------------------------------------+
|  1 | SIMPLE      | c1    | ALL    | PRIMARY                         | NULL               | NULL    | NULL                              | 4212 | Using where; Using temporary; Using filesort |
|  1 | SIMPLE      | c2    | ref    | PRIMARY,clientfile_id,casino_id | PRIMARY            | 4       | casino_beta.c1.clientfile_id      |    1 | NULL                                         |
|  1 | SIMPLE      | c3    | eq_ref | PRIMARY                         | PRIMARY            | 4       | func                              |    1 | Using where                                  |
|  1 | SIMPLE      | c4    | ref    | clientfile_pool_id              | clientfile_pool_id | 4       | casino_beta.c3.clientfile_pool_id |   22 | Using where                                  |
+----+-------------+-------+--------+---------------------------------+--------------------+---------+-----------------------------------+------+----------------------------------------------+
4 rows in set (0.00 sec)