A function that has no partial functional dependencies is in _______ form.

Question

Accepted Answer

The correct option is (2):

The Second Normal Form (2NF) is explicitly defined by the rule that a relation must first be in First Normal Form (1NF) and must not contain any **partial functional dependencies**. A partial dependency occurs only when an attribute that is not part of any candidate key (a non-prime attribute) is functionally dependent on only a *proper subset* of a composite candidate key. Therefore, the absence of partial functional dependencies is the precise necessary and sufficient condition for a relation to be in 2NF. Normalizing to this form is a foundational step in database design, crucial for reducing data redundancy and preventing update anomalies associated with composite keys.

The incorrect option is (3):

The Third Normal Form (3NF) is a stricter normal form than 2NF. A relation that is in 3NF must first satisfy all the conditions of 2NF (which includes having no partial dependencies). Additionally, 3NF requires the elimination of a different type of anomaly known as a **transitive dependency**. A transitive dependency exists when a non-prime attribute is dependent on another non-prime attribute, rather than being solely dependent on the primary key. Since 3NF imposes an extra condition beyond the removal of partial dependencies, it is not the *minimal* or defining normal form described by the question.

The incorrect option is (1):

The Fourth Normal Form (4NF) is a much higher and stricter level of normalization, which focuses on eliminating **non-trivial multivalued dependencies (MVDs)**. A relation in 4NF must already satisfy all the conditions of Boyce-Codd Normal Form (BCNF), which is stricter than 3NF. While a table in 4NF is guaranteed to be free of partial dependencies, 4NF addresses a conceptually different and more complex type of dependency (MVDs), which makes it too strict and the wrong primary answer for the specific condition of eliminating partial functional dependencies.

The incorrect option is (4):

This option is incorrect because **2NF** (Option 2) is the standard, well-defined relational database normal form whose explicit and primary criterion is the elimination of partial functional dependencies. The condition described in the question directly corresponds to the definition of 2NF as laid out by E.F. Codd, the father of the relational model.