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＜電子ブック＞
The Nested Universal Relation Database Model / by Mark Levene
(Lecture Notes in Computer Science. ISSN:16113349 ; 595)

版	1st ed. 1992.
出版者	Berlin, Heidelberg : Springer Berlin Heidelberg : Imprint: Springer
出版年	1992
本文言語	英語
大きさ	X, 182 p : online resource
著者標目	*Levene, Mark author SpringerLink (Online service)
件　名	LCSH:Data structures (Computer science) LCSH:Information theory LCSH:Database management LCSH:Computer science LCSH:Software engineering FREE:Data Structures and Information Theory FREE:Database Management FREE:Theory of Computation FREE:Software Engineering
一般注記	The underlying database models -- The null extended nested relational model -- Null extended data dependencies and the extended chase -- A universal relation model for a nested database -- A universal relation model for a single nested relation -- Concluding remarks and ongoing research 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 HTTP:URL=https://doi.org/10.1007/3-540-55493-9

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