Results 301 to 310 of about 1,731,534 (320)

Relational Databases with Ordered Relations

Logic Journal of the IGPL, 2005
Summary: 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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A Virtual XML Database Engine for Relational Databases

2003
While 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, Jixue Liu, Chengfei Liu, Millist W. Vincent   +3 more
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Object databases as generalizations of relational databases

Computer Standards & Interfaces, 1991
Abstract 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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Equivalence of relational database schemes

Proceedings of the eleventh annual ACM symposium on Theory of computing - STOC '79, 1979
We 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, Yehoshua Sagiv, Catriel Beeri, Alberto O. Mendelzon   +3 more
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Answering queries in relational databases

ACM SIGMOD Record, 1983
This 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, MOSCARINI M, SPYRATOS N.   +2 more
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Assumptions in relational database theory

Proceedings of the 1st ACM SIGACT-SIGMOD symposium on Principles of database systems - PODS '82, 1982
Many 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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Incomplete Information in Relational Databases

Journal of the ACM, 1984
ABSTRACT This paper concerns the semantics of Codd's relational model of data. Formulated are precise conditions that should be satisfied in a semantically meaningful extension of the usual relational operators, such as projection, selection, union, and join, from operators on relations to operators on tables with “null values” of various kinds ...
Witold Lipski, Tomasz Imielinski
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Understand Relational Databases

2019
Understanding the history and theory behind relational databases helps us make sense of things and avoid common traps. But there are also many times when we need to ignore the theory and build practical solutions. This book assumes you are already familiar with relational databases and SQL; the information provided here is not merely introductory, it ...
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Fingerprinting relational databases

Proceedings of the 2006 ACM symposium on Applied computing, 2006
In this paper, we propose a fingerprinting solution to protect valuable numeric relational data from illegal duplications and redistributions. We introduce a twice-embedding scheme. In the first embedding process, we embed a unique fingerprint to identify each recipient to whom the relational data is distributed.
Deyi Li, Jianmin Wang, Fei Guo
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MARC and relational databases

The Electronic Library, 1993
MARC format is a well‐established syntax for transmitting bibliographic records between heterogeneous computer systems. On the other hand, relational databases are the leading technology for the design of the computer systems. Unfortunately, there seem to be some incompatibilities between the two.
Jose Llorens, Asuncion Trenor
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