Database Systems: Concepts, Design and Applications, 2nd Edition

CHAPTER6

Entity Relationship (E-R) Model

6.1 INTRODUCTION

As explained in Chapter 2, Section 2.7.7, an entity-relationship (E-R) model was introduced by P.P Chen in 1976. E-R model is an effective and standard method of communication amongst different designers,programmers and end-users who tend to view data and its use in different ways. It is a non-technical method, which is free from ambiguities and provides a standard and a logical way of visualising the data. It gives precise understanding of the nature of the data and how it is used by the enterprise. It provides useful concepts that allow the database designers to move from an informal description of what users want from their database, to a more detailed and precise description that can ...