Require unique constraint

Any attribute representing an identifier must have a unique constraint or be of type autonumber. This ensures data integrity by preventing duplicate values for attributes intended to serve as unique keys within the model. Ensuring that identifiers are unique is a fundamental aspect of good database design. It prevents inconsistencies and ensures that each entity in the system is uniquely identifiable. By enforcing unique constraints or using autonumber types, the system can maintain data accuracy and avoid conflicts during data entry or processing.