9783540549192 - The Problem of Incomplete Information in Relational Databases (Lecture Notes in Computer Science, 554, Band 554) von Grahne, G??sta (4 Ergebnisse)

Softcover. Zustand: Bon. Ancien livre de bibliothèque. Légères traces d'usure sur la couverture. Edition 1991. Ammareal reverse jusqu'à 15% du prix net de cet article à des organisations caritatives. ENGLISH DESCRIPTION Book Condition: Used, Good. Former library book. Slight signs of wear on the cover. Edition 1991. Ammareal gives back up to 15% of this item's net price to charity organizations.

Zustand: Sehr gut. Zustand: Sehr gut | Sprache: Englisch | Produktart: Bücher | 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.

Taschenbuch. Zustand: Neu. Druck auf Anfrage Neuware - Printed after ordering - 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 queriesdependencies and updates.

Taschenbuch. Zustand: Neu. The Problem of Incomplete Information in Relational Databases | Gösta Grahne | Taschenbuch | viii | Englisch | 1991 | Springer | EAN 9783540549192 | Verantwortliche Person für die EU: Springer Verlag GmbH, Tiergartenstr. 17, 69121 Heidelberg, juergen[dot]hartmann[at]springer[dot]com | Anbieter: preigu.