A foreign key constraint fails in MySQL

Scenario:

drop database databasename;
ERROR 1217 (23000): Cannot delete or update a parent row: a foreign key constraint fails

Resolution:-

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

mysql>  drop database databasename;
Query OK, 2 rows affected (0.06 sec)

mysql> SET FOREIGN_KEY_CHECKS=1;
Query OK, 0 rows affected (0.00 sec)

Ref : - http://stackoverflow.com/questions/3334619/cannot-delete-or-update-a-parent-row-a-foreign-key-constraint-fails