Glossary: SQL Beyond the Basics
Constraint
Also written: constraints
A rule the database enforces on every INSERT and UPDATE, such as NOT NULL, UNIQUE, CHECK or a foreign key. It stops bad data getting in.
Glossary: SQL Beyond the Basics
Also written: constraints
A rule the database enforces on every INSERT and UPDATE, such as NOT NULL, UNIQUE, CHECK or a foreign key. It stops bad data getting in.