In SQL, foreign key constraints can reference only the primary key attributes ofthe referenced relation or other attributes declared to be a superkey using theunique constraint. As a result, total participation constraints on a many-to-manyrelationship set (or on the “one” side of a one-to-many relationship set) cannotbe enforced on the relations created from the relationship set, using primarykey, foreign key, and not null constraints on the relations. Explain why

In SQL, foreign key constraints can reference only the primary key attributes ofthe referenced relation or other attributes declared to be a superkey using theunique constraint. As a result, total participation constraints on a many-to-manyrelationship set (or on the “one” side of a one-to-many relationship set) cannotbe enforced on the relations created from the relationship set, using primarykey, foreign key, and not null constraints on the relations. Explain why

Oracle 12c: SQL

3rd Edition

ISBN:9781305251038

Author:Joan Casteel

Publisher:Joan Casteel

Chapter4: Constraints

Section: Chapter Questions

Problem 1RQ: What is the difference between a PRIMARY KEY constraint and a UNIQUE constraint?

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What is the difference between a PRIMARY KEY constraint and a UNIQUE constraint?
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