Super Key (Relational Algebra)

databases

Definition

Super Key

A subset of attributes $\alpha \subseteq \mathcal{R}$ of a relation $R$ is called super key iff $\alpha \to \mathcal{R}$ ($\alpha$ functionally determines $\mathcal{R}$). In other words, a super key of a relation uniquely identifies a tuple in a relation.

Trivially, the set of all attributes is a super key since $\mathcal{R}\to \mathcal{R}$.