mysql> show variables like 'fo%';
+--------------------+-------+
| Variable_name      | Value |
+--------------------+-------+
| foreign_key_checks | ON    |
+--------------------+-------+
1 row in set (0.00 sec)

mysql> SET FOREIGN_KEY_CHECKS=0;
Query OK, 0 rows affected (0.00 sec)

mysql> show variables like 'fo%';
+--------------------+-------+
| Variable_name      | Value |
+--------------------+-------+
| foreign_key_checks | OFF   |
+--------------------+-------+
1 row in set (0.00 sec)