The Nested Universal Relation Database Model

Levene, Mark

ISBN 10: 3540554939 / ISBN 13: 9783540554936

Published by Springer, 1992

About this Item

Zustand: Sehr gut | Sprache: Englisch | Produktart: Bücher | This monograph describes a method of data modelling whosebasic aim is to make databases easier to use by providingthem with logical data independence. To achieve this, thenested UR (universal relation) model is defined by extendingthe classical UR model to nested relations. Nested relationsgeneralize flat relations and allow hierarchicallystructured objects to be modelled directly, whereas theclassical UR model allows the user to view the database asif it were composed of a single flat relation. The authorpresents a comprehensive formalisation of the nestedrelational model, which incorporated null values into themodel. Functional data dependencies and the classical notionof lossless decomposition are extended to nested relationsand an extended chase procedure is defined to test thesatisfaction of the data dependencies. The nested UR modelis defined, and the classical UR model is shown to be aspecial case of the nested model.This implies that an URinterface canbe implemented by using the nested UR model,thus gaining the full advantages of nested relations overflat relations.

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Bibliographic Details

• Title: The Nested Universal Relation Database Model
• Publisher: Springer
• Publication Date: 1992
• Language: English
• ISBN 10: 3540554939
• ISBN 13: 9783540554936
• Binding: Soft cover
• Condition: Sehr gut
• Seller catalogs:
  • Bücher

About this title

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.