منابع مشابه
A relational algebra for SPARQL
The SPARQL query language for RDF provides Semantic Web developers with a powerful tool to extract information from large datasets. This report describes a transformation from SPARQL into the relational algebra, an abstract intermediate language for the expression and analysis of queries. This makes existing work on query planning and optimization available to SPARQL implementors. A further tra...
متن کاملThe relational data model and relational algebra
The early days of database engines (1960’s) saw several competing “data models” (the formal specifications for how the system represents and reasons about data). Academic researchers had proposed several models that were rich, expressive, and provided admirable data independence, but that were impossible to implement efficiently. The models used by working systems, on the other hand, tended to ...
متن کاملRelational Algebra Operations
Relational algebra is the instruction set of relational database systems. In this paper, a set of relational algebra operations are described and slightly enhanced for improved efficiency. How these routines can be implemented on a parallel database computer is described in detail. Four operations are handled: projection, join, aggregation and division. The implemantation is heavyly based on ha...
متن کاملTeaching Relational Algebra and Relational Calculus: A Programming Approach
This paper describes how relational algebra and relational calculus can be taught using a programming approach. This is in contrast to the mathematical presentation of these topics in most database textbooks. For relational algebra, a function library implemented with Visual FoxPro allows queries to be written as a sequence of function calls--one call per relational algebra operation. For relat...
متن کاملA Temporal Relational Algebra as Basis for Temporal Relational Completeness
We define a tenlporal algebra that is applicable to any temporal relational data model supporting discrete linear bounded time. This algebra has the five basic relational algebra operators extended to the temporal domain and an operator of linear recursion. We show that this algebra has the expressive power of a safe temporal calculus based on the predicate temporal logic with the until and sin...
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ژورنال
عنوان ژورنال: Mobile Information Systems
سال: 2011
ISSN: 1574-017X,1875-905X
DOI: 10.1155/2011/678759