mysql> select team.name, count(*) as nb_joueur
    -> from team
    -> join player on team.id = player.team_id
    -> group by team.id
    -> order by nb_joueur desc;
+------------+-----------+
| name       | nb_joueur |
+------------+-----------+
| Gryffindor |        36 |
| Slytherin  |        21 |
| Ravenclaw  |        15 |
| Hufflepuff |        12 |
+------------+-----------+
4 rows in set (0.00 sec)

mysql> select team.name
    -> from player
    -> join team on team.id=player.team_id
    -> group by team.name
    -> having count(player.id) > 14
    -> order by name;
+------------+
| name       |
+------------+
| Gryffindor |
| Ravenclaw  |
| Slytherin  |
+------------+
3 rows in set (0.00 sec)

mysql> select concat(firstname, ' ', lastname) as fullname
    -> from wizard
    -> join player ON wizard_id=wizard.id
    -> join team ON team_id=team.id
    -> where team.name='Gryffindor' and dayofweek(enrollment_date) = 2
    -> order by enrollment_date;
+----------------------+
| fullname             |
+----------------------+
| George Weasley       |
| Alice Longbottom     |
| Cadogan              |
| Godric Gryffindor    |
| Sirius Black         |
| Aberforth Dumbledore |
| Augusta Longbottom   |
+----------------------+
7 rows in set (0.00 sec)