Synergistic database design with an extended Entity-Relationship model
Entity-Relationship (ER) models and extended Entity-Relationship (EER) models has limitations and problems.
The problems are:
Embley and Ling propose an approach in their paper “Synergistic Database Design with an Extended Entity-Relationship Model” that solves these two problems. Their approach can be summarized as:
Embley and Ling introduce an improved EER model called E²R (read “E-squared-R”). E²R is based on the ER model. It has many ideas such as generalization/specialization and lexical entity sets from semantic data models.
In the E²R model designers don’t have to distinguish between attributes and entities and it also supports the normalization at the model level.
So the major problems of ER models can be solved with their introduced model. Synergistic database design occurs as a designer interactively manipulates an E²R diagram until it has the properties that are desired. Design is done by transforming a given E²R into a normalized E²R model that is guaranteed to generate normalized relations.