Constraints are declaractions of conditions about the database that must remain true. These include attributed-based, tuple-based, key, and referential integrity constraints. The system checks for the violation of the constraints on actions that may cause

A database triggers is stored PL/SQL program unit associated with a specific database table or view. The code in the trigger defines the action the database needs to perform whenever some database manipulation (INSERT, UPDATE, DELETE) takes place.

Transaction Model, Oracle transactions are atomic. No commit or rollback are allowed in a trigger. Maximum trigger size,