Drop all tables, constraints, and sequences within an Oracle schema.
refer link: https://snipt.net/Fotinakis/drop-all-tables-and-constraints-within-an-oracle-schema/
BEGINFOR c IN (SELECT table_name FROM user_tables) LOOPEXECUTE IMMEDIATE ('DROP TABLE ' || c.table_name || ' CASCADE CONSTRAINTS');END LOOP;FOR s IN (SELECT sequence_name FROM user_sequences) LOOPEXECUTE IMMEDIATE ('DROP SEQUENCE ' || s.sequence_name);END LOOP;END;