Results 191 to 200 of about 311,800 (213)
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Construction of relations in relational databases
ACM Transactions on Database Systems, 1980Using a nonprocedural language for query formulation requires certain automatization of a query answering process. Given a query for creation of a new relation, the problem is to find an efficient procedure which produces this relation from a given relational database. We concentrate upon sequences of join operations which losslessly produce a relation
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, 2013 In mathematics a binary relation between two sets \(A\) and \(B\) is a collection of ordered pairs \((a,b)\) belonging to the cartesian product \(A\,\times \,B\). In this chapter we present some of the general properties of relations and their operations, as well some special types of relations defined over the same set.
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Relational Databases with Ordered Relations
Logic Journal of the IGPL, 2005Summary: The paper deals with expressing preferences in the framework of the relational data model. Preferences have usually a form of a partial ordering. Therefore the question arises how to provide the relational data model with such an ordering.
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The use of a database machine for supporting relational databases
ACM SIGARCH Computer Architecture News, 1978One of the goals in the design of database machines of the future is their generality. In addition to being capable of carrying out the common database management functions with high reliability and performance, some of these machines are intended to support more than one data model. A specific database machine, known as the DBC, is intended to support
Jayanta Banerjee, David K. Hsiao
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Physical database design for relational databases
ACM Transactions on Database Systems, 1988This paper describes the concepts used in the implementation of DBDSGN, an experimental physical design tool for relational databases developed at the IBM San Jose Research Laboratory. Given a workload for System R (consisting of a set of SQL statements and their execution frequencies), DBDSGN suggests physical configurations for efficient performance.
Paolo Tiberio +2 more
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Equivalence of relational database schemes
Proceedings of the eleventh annual ACM symposium on Theory of computing - STOC '79, 1979We investigate the question of when two database schemes embody the same information. We argue that this question reduces to the equivalence of the sets of fixed points of the project-join mappings associated with the two database schemes in question.
Jeffrey D. Ullman +3 more
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Answering queries in relational databases
ACM SIGMOD Record, 1983This paper concerns query answering in relational databases. We assume a universe U of attributes and a set of values associated with each attribute. A database scheme is a given collection R = {1, 2, ..., n} of subsets of U, called relation schemes. A query in R is any subset of U. We call "context" any joinable subset of R.
D'ATRI, ALESSANDRO +2 more
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A Virtual XML Database Engine for Relational Databases
2003While XML is emerging as the universal format for publishing and exchanging data on the Web, most business data is still stored and maintained in relational DBMSs. To enable eBusiness database applications, Web access to the legacy data managed by DBMSs needs to be provided.
Minyi Guo +3 more
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Object databases as generalizations of relational databases
Computer Standards & Interfaces, 1991Abstract One attractive approach to object databases is to see them as potentially an evolutionary development from relational databases. This paper concentrates on substantiating the technical basis for this claim, and illustrates it in some detail with an upwards-compatible extension of ANSI SQL2 for conventional objects.
David Beech, Ç. Özbütün
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Assumptions in relational database theory
Proceedings of the 1st ACM SIGACT-SIGMOD symposium on Principles of database systems - PODS '82, 1982Many results in relational database theory on the structure of dependencies, query languages, and databases in general have now been established. However, neither (a) the reliance of these results on various assumptions, nor (b) the desirability or reasonableness of these assumptions themselves have been closely examined.
ATZENI, Paolo, PARKER DS
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