In third normal form, the exception to the rule that a non-key attribute cannot define another non-key attribute is ____.
A) if the defining attribute is a candidate key
B) if the defined attribute is a candidate key
C) if the defining attribute is a foreign key
D) if the defined attribute is a foreign key
E) None of the above.

Question

Quizplus · Accepted Answer

In third normal form, a non-key attribute can define another non-key attribute only if the defining attribute is a candidate key. This is because a candidate key uniquely identifies a record and eliminates the possibility of a transitive dependency. Therefore, option A is the correct choice.

In Third Normal Form, the Exception to the Rule That