Normal form for sets of not-necessarily normalized relations

Abstract

A normal form for sets of not-necessarily normalized relations, called NF-N3, is defined. This normal form not only removes local redundancy within each single relation but also removes global redundancy among relations. Properties pertaining to this normal form are given. The main differences between this normal form and others are discussed. Two methods for obtaining sets of not-necessarily normalized relations that are in NF-N3, namely, a decomposition method and a method that uses the entity-relationship (ER) approach are given. A description is given of how the ER approach together with the concepts of a normal-form ER diagram and functional dependency theory can be used for designing a relational database schema that allows the existence of non-first-normal-form relations. The set of not-necessarily normalized relations generated is in NF-N3. The correspondence between not-necessarily normalized relations and hierarchical definition trees of hierarchical databases is presented.