The Nested Universal Relation Database Model

✍ Scribed by M. Levene (eds.)

• Publisher: Springer-Verlag Berlin Heidelberg
• Year: 1992
• Tongue: English
• Leaves: 178
• Series: Lecture Notes in Computer Science 595
• Edition: 1
• Category: Library

✦ Synopsis

This monograph describes a method of data modelling whose basic aim is to make databases easier to use by providing them with logical data independence. To achieve this, the nested UR (universal relation) model is defined by extending the classical UR model to nested relations. Nested relations generalize flat relations and allow hierarchically structured objects to be modelled directly, whereas the classical UR model allows the user to view the database as if it were composed of a single flat relation. The author presents a comprehensive formalisation of the nested relational model, which incorporated null values into the model. Functional data dependencies and the classical notion of lossless decomposition are extended to nested relations and an extended chase procedure is defined to test the satisfaction of the data dependencies. The nested UR model is defined, and the classical UR model is shown to be a special case of the nested model.This implies that an UR interface canbe implemented by using the nested UR model, thus gaining the full advantages of nested relations over flat relations.

✦ Table of Contents

Introduction....Pages 1-9
The underlying database models....Pages 11-33
The null extended nested relational model....Pages 35-75
Null extended data dependencies and the extended chase....Pages 77-107
A universal relation model for a nested database....Pages 109-135
A universal relation model for a single nested relation....Pages 137-157
Concluding remarks and ongoing research....Pages 159-161

✦ Subjects

Database Management; Computation by Abstract Devices; Software Engineering