An extended entity-relationship model. Fundamentals and pragmatics (Q1315519)

Ever since the Entity-Relationship model has been proposed in 1976, there have been a number of extensions to improve the semantic expressiveness of data modeling. In this book, the author proposes a new data model, namely the extended Entity-Relationship model and its various consequences in terms of data modeling and the database query language. The author has emphatically provided the precise formal semantics of the proposed data model which other semantic data models lack and also has adequately utilized such formalism in the sequent. This book consists of four major sections: First, this book starts with a comprehensive introduction to the extended Entity-Relationship model in a formal and mathematical way. Second, the author formally defines an extended Entity-Relationship calculus that supports all concepts of the extended Entity-Relationship model as well as data operations on the attribute domains and aggregate functions. The proposed tuple calculus can be considered as a high-level and descriptive query language and at the same time a constraint language for the extended Entity-Relationship model. Third, a PROLOG implementation of the full model and the extended Entity-Relationship calculus is addressed. The system that can be regarded as a design tool provides a clean and calculus-oriented interface to the user so that the user can work with the proposed language only. Lastly, the book presents a translation of a subset of the relational query language SQL, the de facto standard database language, into a subset of the extended Entity-Relationship calculus. The subset considered is relationally complete and also includes aggregation (e.g., COUNT, AVG, etc.) and grouping features (e.g., GROUP BY, HAVING, etc.).