functional dependency

functional dependency
A constraint between two sets of attributes in a relation.

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  • Functional dependency — A functional dependency (FD) is a constraint between two sets of attributes in a relation from a database.Given a relation R , a set of attributes X in R is said to functionally determine another attribute Y , also in R , (written X → Y ) if and… …   Wikipedia

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  • Functional decomposition — refers broadly to the process of resolving a functional relationship into its constituent parts in such a way that the original function can be reconstructed (i.e., recomposed) from those parts by function composition. In general, this process of …   Wikipedia

  • Dependency theory (database theory) — Dependency theory is a subfield of database theory which studies implication and optimization problems related to logical constraints, commonly called dependencies, on databases. The best known class of such dependencies are functional… …   Wikipedia

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  • Dependency diagram — A dependency diagram is a visual representation of a dependency graph. Dependency diagrams are integral to software development, outlining the complex, interrelationships of various functional elements. Typically in a dependency diagram, arrows… …   Wikipedia

  • Transitive dependency — In mathematics, a transitive dependency is a functional dependency which holds by virtue of transitivity. A transitive dependency can occur only in a relation that has three or more attributes. Let A, B, and C designate three distinct attributes… …   Wikipedia

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