functional dependency
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Related to functional dependency: normalization, Transitive dependency
functional dependency
(database)Given a relation R (in a relational database),
attribute Y of R is functionally dependent on attribute X of R
and X of R functionally determines Y of R (in symbols R.X ->
R.Y) if and only if each X in R has associated with it
precisely one Y in R (at any one time). Attributes X and Y
may be composite.
This is very close to a function in the mathematical sense.
This is very close to a function in the mathematical sense.
This article is provided by FOLDOC - Free Online Dictionary of Computing (foldoc.org)
functional dependency
A dependent relationship between two data elements in a relational database. Used to define normalization, a functional dependency (FD) states that one data element is dependent on another. For example, a social security number (SSN) refers to only one employee (EMP). Expressed as SSN->EMP, employee is dependent on social security number. A product number refers to one product (PRODNO->PRODNAME), and a customer number refers to one customer name (CUSTNO->CUSTNAME). See normalization and transitive dependency.Copyright © 1981-2019 by The Computer Language Company Inc. All Rights reserved. THIS DEFINITION IS FOR PERSONAL USE ONLY. All other reproduction is strictly prohibited without permission from the publisher.