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The Problem of Incomplete Information in Relational Databases : Lecture Notes in Engineering - Gosta Grahne

The Problem of Incomplete Information in Relational Databases

Lecture Notes in Engineering

Paperback Published: 13th November 1991
ISBN: 9783540549192
Number Of Pages: 164

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In a relational database the information is recorded as rowsin tables. However, in many practical situations theavailable information is incomplete and the values for somecolumns are missing. Yet few existing database managementsystems allow the user to enter null values in the database.This monograph analyses the problems raised by allowing nullvalues in relational databases. The analysis coverssemantical, syntactical, and computational aspects.Algorithms for query evaluation, dependency enforcement andupdates in the presence of null values are also given.The analysis of the computational complexity of thealgorithms suggests that from a practical point of view thedatabase should be stored as Horn tables, which aregeneralizations of ordinary relations, allowing null valuesand Horn clause-like restrictions on these null values. Horntables efficiently support a large class of queries,dependencies and updates.

Relational databases.- Semantic aspects of incomplete information.- Syntactic and algorithmic aspects of incomplete information.- Computational complexity aspects of incomplete information.- Some conclusive aspects.

ISBN: 9783540549192
ISBN-10: 3540549196
Series: Lecture Notes in Engineering
Audience: General
Format: Paperback
Language: English
Number Of Pages: 164
Published: 13th November 1991
Publisher: Springer-Verlag Berlin and Heidelberg Gmbh & Co. Kg
Country of Publication: DE
Dimensions (cm): 23.39 x 15.6  x 0.94
Weight (kg): 0.25