Dropping a Constraint

You drop a constraint using the DROP CONSTRAINT clause of ALTER TABLE.

ALTER TABLE emp
DROP CONSTRAINT yourConstraintName;

1. Adding a Constraint with CHECK
2. Adding a NOT NULL Constraint
3. Adding a FOREIGN KEY Constraint
4. ON DELETE CASCADE
5. ON DELETE SET NULL
6. Adding a UNIQUE Constraint
7. CHECK constraint
8. Multiple Constraints
9. Dropping a Constraint
10. Disabling a Constraint
11. Enabling a Constraint
12. Deferred Constraints
13. Getting Information on Constraints:user_constraints and all_constraints