How is a constraint disabled?
How is a constraint disabled?
Rating:
A constraint is disabled using the DISABLE clause of the ALTER TABLE statement. When disabling a constraint, the VALIDATE or NOVALIDATE keyword can be used with the DISABLE clause.
The VALIDATE keyword specifies that the constraint is disabled and all indexes used to enforce the constraint are dropped. However, the constraint still remains valid. In this state, Data Manipulation Language (DML) statements are not allowed on the table. This is because new changes in the table cannot be verified, as the constraint is disabled, and the existing data in the table has to comply with the constraint, as the constraint is still valid.
The NOVALIDATE keyword specifies that the constraint is disabled and invalidated. The existing data in the table and new data being inserted in the table may violate the constraint.
Rating:
Other articles
- What is SYSDBA?
- What is the syntax for creating an index?
- What is a log switch?
- What is library cache ?
- What is object privilege?