Ayudaa!!

[roskiya]

mysql> describe ejercicio;
+-------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------------+--------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| asignatura | varchar(30) | YES | | NULL | |
| fecha | date | YES | | NULL | |
| descripcion | varchar(150) | YES | | NULL | |
+-------------+--------------+------+-----+---------+----------------+
4 rows in set (0.00 sec)





mysql> describe expediente;
+-------+---------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+---------+------+-----+---------+-------+
| num | int(11) | NO | PRI | 0 | |
| id | int(11) | NO | PRI | 0 | |
| nota | float | YES | | NULL | |
+-------+---------+------+-----+---------+-------+
3 rows in set (0.02 sec)





mysql> describe alumno;
+-----------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-----------+--------------+------+-----+---------+----------------+
| num | int(11) | NO | PRI | NULL | auto_increment |
| nombre | varchar(60) | YES | | NULL | |
| apellidos | varchar(100) | YES | | NULL | |
| grupo | int(11) | YES | | NULL | |
+-----------+--------------+------+-----+---------+----------------+
4 rows in set (0.02 sec)