Results 231 to 240 of about 36,093 (262)

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 ...
Tomasz Imielinski, Witold Lipski Jr.
openaire   +1 more source

Compiling subsumption to relational databases

Intelligenza Artificiale: The international journal of the AIxIA, 2013
We investigate on the possibility of transforming concepts in Description Logics into relational databases and queries in such a way that subsumption between the original concepts can be decided as query answering over a database. For the positive results, we show a translation of -concepts into pairs (database, query) such that, in order to decide ...
Eufemia Tinelli, Francesco M. Donini, DI SCIASCIO, Eugenio   +2 more
openaire   +2 more sources

An Algebraic Theory of Relational Databases

Bell System Technical Journal, 1983
In this paper we present a theory of relational database systems based on the partition lattice, which represents a new mathematical approach to the structure of relational database systems. A partition lattice can be defined for any given relation.
openaire   +2 more sources

Nulls in relational databases

ACM SIGMOD Record, 1989
This paper discusses the semantic issues related to null values problem in relational databases. We argue that the proposed set of maybe operations with the three valued logic is still not adequate and needs further enhancements.
openaire   +1 more source

On the normalization of relational databases

Information Processing Letters, 1979
B. Srinivasan, V. Rajaraman
openaire   +2 more sources

Designing Relational Databases

2000
Candace C. Fleming, Barbara von Halle
openaire   +1 more source

System R

ACM Transactions on Database Systems, 1976
M M Astrahan, D D Chamberlin, David K Hsiao   +2 more
exaly  

Incorporating computed relations in relational databases

Proceedings of the 1981 ACM SIGMOD international conference on Management of data - SIGMOD '81, 1981
David Maier 0001, David Scott Warren
openaire   +1 more source

A new method to estimate null values in relational database systems based on automatic clustering techniques

Information Sciences, 2005
Shyi-Ming Chen
exaly  

Reverse engineering of relational databases: Extraction of an EER model from a relational database

Data and Knowledge Engineering, 1994
Veda C Storey
exaly