mysql> select * from Abteilungen;
Empty set (0.02 sec)
mysql> insert into Abteilungen values ('SAI',
-> 'Abteilung Angewandte Informationsverarbeitung',
-> NULL);
Query OK, 1 row affected (0.00 sec)
mysql> insert into Angestellte values
-> ('swg', 'Franz Schweiggert', 'SAI');
Query OK, 1 row affected (0.01 sec)
mysql> update Abteilungen set chef = 'swg'
-> where abtid = 'SAI';
Query OK, 1 row affected (0.07 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> delete from Abteilungen where abtid = 'SAI';
ERROR 1217: Cannot delete or update a parent row:
a foreign key constraint fails
mysql> delete from Angestellte where persid = 'swg';
Query OK, 1 row affected (0.00 sec)
mysql> select abtid, chef from Abteilungen;
+-------+------+
| abtid | chef |
+-------+------+
| SAI | NULL |
+-------+------+
1 row in set (0.01 sec)
mysql>
|