CHECK CONSTRAINT ALTER TABLE ADD CONSTRAINT

Using an ALTER TABLE statement

The syntax for creating a check constraint in an ALTER TABLE statement in Oracle is:

ALTER TABLE table_name
ADD CONSTRAINT constraint_name CHECK (column_name condition) [DISABLE];

The DISABLE keyword is optional. If you create a check constraint using the DISABLE keyword, the constraint will be created, but the condition will not be enforced.

Example

ALTER TABLE suppliers
ADD CONSTRAINT check_supplier_name
  CHECK (supplier_name IN ('IBM', 'Microsoft', 'NVIDIA'));