select * from pet order by field(species, 'cat', 'dog', 'bird');

 

+----------+--------+---------+------+------------+------------+
| name | owner | species | sex | birth | death |
+----------+--------+---------+------+------------+------------+
| Puffball | Diane | hamster | f | 1999-03-30 | NULL |
| Slim | Benny | snake | m | 1996-04-29 | NULL |
| Claws | Gwen | cat | m | 1994-03-17 | NULL |
| Fluffy | Harold | cat | f | 1993-02-04 | NULL |
| Buffy | Harold | dog | f | 1989-05-13 | NULL |
| Bowser | Diane | dog | m | 1979-08-31 | 1995-07-29 |
| Fang | Benny | dog | m | 1990-08-27 | NULL |
| Chirpy | Gwen | bird | f | 1998-09-11 | NULL |
| Whistler | Gwen | bird | N | 1997-12-09 | NULL |
+----------+--------+---------+------+------------+------------+

이렇게 정의 가능하다.