NDLI: Calculating constraints on relational expression

Content Provider	ACM Digital Library
Author	Klug, A.
Copyright Year	1980
Abstract	This paper deals with the problem of determining which of a certain class of constraints hold on a given relational algebra expression where the base relations come from a given schema. The class of constraints includes functional dependencies, equality of domains, and constancy of domains. The relational algebra consists of projection, selection, restriction, cross product, union, and difference. The problem as given is undecidable, but if set difference is removed from the algebra, there is a solution. Operators specifying a closure function (similar to functional dependency closure on one relation) are defined; these will generate exactly the set of constraints valid on the given relational algebra expression. We prove that the operators are sound and complete.
Starting Page	260
Ending Page	290
Page Count	31
File Format	PDF
ISSN	03625915
e-ISSN	15574644
DOI	10.1145/320613.320615
Volume Number	5
Issue Number	3
Journal	ACM Transactions on Database Systems (TODS)
Language	English
Publisher	Association for Computing Machinery (ACM)
Publisher Date	1980-09-01
Publisher Place	New York
Access Restriction	One Nation One Subscription (ONOS)
Subject Keyword	Views Constraints Derivation rules Eompleteness Functional dependencies
Content Type	Text
Resource Type	Article
Subject	Information Systems

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Calculating constraints on relational expression