NORMAL FORM FOR ENTITY-RELATIONSHIP DIAGRAMS.

Abstract

A normal form for entity-relationship diagrams and the objectives for such a normal form are presented. A normal form entity-relationship diagram may consist of composite attributes, multivalued attributes, and special types of relationship sets such as existence dependent, identifier dependent, ISA, UNION, INTERSECT, and DECOMPOSE relationships. A comprehensive algorithm is given to translate a normal form entity-relationship diagram to a set of relations. It is shown that all relations generated are either in third normal form or fifth normal form. General guidelines and detailed steps for converting an entity-relationship diagram to a normal form entity-relationship diagram are presented. These steps can also be used as guidelines for designing databases using the entity-relationship approach.