CONSTRAINTS

CONSTRAINTS

Constraints enforce limits to the Data or type of data that can be inserted/deleted/updated from a relation. The entire cause of constraints is to preserve the data integrity all through an insert/delete/update right into a table.

Types of constraints

•     NOT NULL
•    DEFAULT
•     UNIQUE
•      Key Constraints – PRIMARY KEY, FOREIGN KEY
•      Mapping constraints
•      CHECK
•      Domain constraints