The Problem of Incomplete Information in Relational Databases: 554 (Lecture Notes in Computer Science, 554) - Tapa blanda

Grahne, G??sta

 
9783540549192: The Problem of Incomplete Information in Relational Databases: 554 (Lecture Notes in Computer Science, 554)
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ISBN 10: 3540549196 ISBN 13: 9783540549192
Editorial: Springer, 2008

Sinopsis

In a relational database the information is recorded as rows in tables. However, in many practical situations the available information is incomplete and the values for some columns are missing. Yet few existing database management systems allow the user to enter null values in the database. This monograph analyses the problems raised by allowing null values in relational databases. The analysis covers semantical, syntactical, and computational aspects. Algorithms for query evaluation, dependency enforcement and updates in the presence of null values are also given. The analysis of the computational complexity of the algorithms suggests that from a practical point of view the database should be stored as Horn tables, which are generalizations of ordinary relations, allowing null values and Horn clause-like restrictions on these null values. Horn tables efficiently support a large class of queries, dependencies and updates.

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Reseña del editor

In a relational database the information is recorded as rows in tables. However, in many practical situations the available information is incomplete and the values for some columns are missing. Yet few existing database management systems allow the user to enter null values in the database. This monograph analyses the problems raised by allowing null values in relational databases. The analysis covers semantical, syntactical, and computational aspects. Algorithms for query evaluation, dependency enforcement and updates in the presence of null values are also given. The analysis of the computational complexity of the algorithms suggests that from a practical point of view the database should be stored as Horn tables, which are generalizations of ordinary relations, allowing null values and Horn clause-like restrictions on these null values. Horn tables efficiently support a large class of queries, dependencies and updates.

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Editorial
Springer
Año de publicación
2008
Idioma
Inglés
ISBN 10 
3540549196
ISBN 13 
9783540549192
Encuadernación
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Número de páginas
172
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Otras ediciones populares con el mismo título

9780387549194: The Problem of Incomplete Information in Relational Databases (Lecture Notes in Computer Science)

Edición Destacada

ISBN 10:  0387549196 ISBN 13:  9780387549194
Editorial: Springer Verlag, 1992
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