Disabling a Constraint

By default, a constraint is enabled when you create it. You can initially disable a constraint by adding DISABLE to the end of the CONSTRAINT clause.

ALTER TABLE employee
ADD CONSTRAINT my_uq UNIQUE (ename) DISABLE;

You can disable an existing constraint using the DISABLE CONSTRAINT clause of ALTER TABLE. The following example disables the yourConstraintName constraint:

ALTER TABLE employee
DISABLE CONSTRAINT yourConstraintName;

CASCADE after DISABLE CONSTRAINT disables all constraints that depend on the specified constraint. CASCADE can also disable a primary key or unique constraint that is part of a foreign key constraint.

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