Sql avance

1er requête :

mysql> SELECT name, COUNT(*) as nb_player FROM team
    -> JOIN player ON team_id=team.id
    -> GROUP BY name;
+------------+-----------+
| name       | nb_player |
+------------+-----------+
| Gryffindor |        36 |
| Ravenclaw  |        15 |
| Slytherin  |        21 |
| Hufflepuff |        12 |
+------------+-----------+

2eme requete : 

mysql> SELECT name, COUNT(*) as team_full FROM team
    -> JOIN player ON team_id=team.id
    -> GROUP BY name
    -> HAVING team_full >= 14;
+------------+-----------+
| name       | team_full |
+------------+-----------+
| Gryffindor |        36 |
| Ravenclaw  |        15 |
| Slytherin  |        21 |
+------------+-----------+

3eme requete :

mysql> SELECT DATE_FORMAT(enrollment_date, "%Y %M %d %W") AS enrollment_date,
    -> firstname, lastname, name FROM player
    -> JOIN wizard ON wizard.id=player.wizard_id
    -> JOIN team ON player.team_id=team.id WHERE name = "Gryffindor"
    -> GROUP BY enrollment_date HAVING DAYOFWEEK(enrollment_date) = 2
    -> ORDER BY enrollment_date;
+-------------------------+-----------+------------+------------+
| enrollment_date         | firstname | lastname   | name       |
+-------------------------+-----------+------------+------------+
| 1991 August 26 Monday   | George    | Weasley    | Gryffindor |
| 1992 February 17 Monday | Alice     | Longbottom | Gryffindor |
| 1993 August 30 Monday   | Godric    | Gryffindor | Gryffindor |
| 1993 January 04 Monday  | Cadogan   |            | Gryffindor |
| 1994 January 10 Monday  | Sirius    | Black      | Gryffindor |
| 1995 April 24 Monday    | Aberforth | Dumbledore | Gryffindor |
| 1999 October 25 Monday  | Augusta   | Longbottom | Gryffindor |
+-------------------------+-----------+------------+------------+