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Time and Relational Theory, 2nd Edition
book

Time and Relational Theory, 2nd Edition

by C.J. Date, Hugh Darwen, Nikos Lorentzos
August 2014
Advanced content levelAdvanced
560 pages
15h 32m
English
Morgan Kaufmann
Content preview from Time and Relational Theory, 2nd Edition
Chapter 2

Relational Algebra

This chapter describes and illustrates a set of generic, read-only operators on relations that together constitute what’s called the relational algebra. The algebraic closure property is explained and its significance discussed in detail. Operators described include RENAME, restrict, project, UNION, INTERSECT, MINUS, JOIN, TIMES, MATCHING, NOT MATCHING, EXTEND (two versions), GROUP, and UNGROUP. Image relations are explained, including in particular a discussion of their usefulness in formulating summarization queries. Relational comparisons (relation equality, relation inclusion, etc.) are discussed, as are primitive operations and the important notion of relational completeness. The use of WITH in formulating complicated ...

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Publisher Resources

ISBN: 9780128006313