TODO:
You have table A, and Table B. Table A has a foreign key to table B, and table B has a foreign key to table A. You need to delete data from table A, but cannot because of the foreign key on Table B.
SOLUTION:
ALTER TABLE employee NOCHECK CONSTRAINT ALL
delete employee where id=100
ALTER TABLE employee WITH CHECK CHECK CONSTRAINT ALL
NOTES:
This will allow you to delete data when there arecircular foreign keys.