Second Normal Form

relational-algebra

Definition

Second Normal Form

A schema $\mathcal{R}$ with functional dependencies $F$ is in second normal form if all non-prime attribute $A\in \mathcal{R}$ are fully functional dependent on every key candidate $k_j$ of the relation.

$$(k_j\to A)\in F^{+}\wedge k_j\text{ is fully functionally dependent}$$

In other words, a schema is in second normal form if it does not consist of any partial dependencies. No non-key-candidate attribute should determine any other attribute in the relation.