A primary key is which of the following?

A. no primary key attribute may be null. B. no primary key can be composite. C. no primary key may be unique. D. no primary key may be equal to a value in a foreign key.

A. One relation is created. B. Two relations are created. C. Three relations are created. D. Four relations are created.

A. First normal form B. Second normal form C. Third normal form D. Fourth normal form

A. Any attribute B. The same thing as a primary key C. An attribute that serves as the primary key of another relation D. An attribute that serves no purpose