Check for dependant foreign keys before dropping Primary Key

SELECT A.owner foreign_owner, a.table_name foreign_table, b.owner primary_owner, b.table_name primary_table
from dba_constraints a, dba_constraints b
where a.r_constraint_name = b.constraint_name and a.constraint_type = 'R'
and b.constraint_type = 'P' and b.table_name = 'DEPT';