mysql> select count(nom) as nb_hab, libfonction from habitant group by libfonction order by nb_hab;
+--------+-------------+
| nb_hab | libfonction |
+--------+-------------+
|      1 | barde       |
|      1 | chef        |
|      1 | druide      |
|      1 | poissonnier |
|      1 | retrait     |
|      4 | guerrier    |
+--------+-------------+
6 rows in set (0.00 sec)