The attribute(s) that make up a foreign key in a relation of a database ____.
A) cannot appear in another relation of the database
B) may or may not appear in another relation of the database
C) must appear in another relation of the database
D) must have unique values in the relation in which it is a foreign key
E) must be part of the primary key in the relation in which it is a foreign key

Question

Quizplus · Accepted Answer

A foreign key in a relation of a database must refer to a primary key in another relation, hence it must appear in another relation of the database. Option A is incorrect because the same attribute(s) may appear in another relation as long as they are not a primary key or part of one. Option B is incorrect because a foreign key has to refer to a primary key in another relation. Option D is incorrect because the values of a foreign key do not have to be unique in the relation in which it is a foreign key. Option E is incorrect because the foreign key does not have to be part of the primary key in the relation in which it is a foreign key, although it may be.

The Attribute(s) That Make Up a Foreign Key in a Relation