In database normalization, which normal form requires that all non-key attributes be fully functionally dependent on the primary key, eliminating partial dependencies?

• A. 1NF
• B. 2NF
• C. 3NF
• D. BCNF

Answer: (B)

This question targets how partial dependencies are removed through a specific level of normalization. In the second normal form, every non-prime attribute must depend on the entire primary key. That means if the primary key is composite, no non-key attribute should be determined by just a part of that key.

Think of a table where the primary key is made up of two attributes, say A and B. If a non-key attribute depends only on A (or only on B), that’s a partial dependency. Second normal form requires such partial dependencies to disappear, so each non-prime attribute must rely on the whole combination (A and B) to be determined.

A practical consequence is that if the key isn’t composite (only a single attribute), there aren’t any partial dependencies to worry about, so the table would already satisfy second normal form as long as it’s in first normal form.

Thus, the normal form that enforces full functional dependency of non-key attributes on the primary key and eliminates partial dependencies is the second normal form. For example, splitting a table with (StudentID, CourseID) as the key into separate tables for students, courses, and enrollments ensures non-key attributes depend on the entire key in their respective relations.