Extended Entity Relationship Modeling

Extended Entity Relationship Modeling

Sikha Bagui (University of West Florida, USA)
Copyright: © 2005 |Pages: 7
DOI: 10.4018/978-1-59140-560-3.ch040
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Abstract

With the rising complexity of database applications, the basic concepts of Entity-Relationship (ER) modeling (as originally developed by Chen, 1976) were no longer sufficient. So the basic ER model was extended to include generalizations and specializations (Bagui & Earp, 2003; Elmasri & Navathe, 2003) and the concept of categories (Elmasri, Weeldreyer & Hevner, 1985). An ER model which includes all the concepts of the original ER model and the additional concepts of generalizations/specializations and categories is often referred to as the Extended ER (EER) model (Elmasri & Navathe, 2003). In this short paper, we shed some light on these relationship concepts, concepts that database designers often find difficult to model directly (Engels et al., 1992/1993). We also discuss the mapping rules for generalizations/specializations and categories. Important contributions in this area are also reported in (Elmasri et al., 1985; Markowitz & Shoshani, 1992; Dey, Storey & Barron, 1999; Wiederhold & Elmasri, 1980). Song, Evans, and Park (1995) also give a good comparative analysis of other types of ER diagrams and their notations.

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