functional dependency

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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.

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.
References in periodicals archive ?
The implementation of the construction project various structural and functional dependencies are taken into account.
Among specific topics are a deep web database sampling method based on high correlation keywords, an algorithm for predicting frequent patterns over data streams based on an associated matrix, a load balancing algorithm in a distributed sonar data stream management system, and a multilayer method of schema matching based on semantic and functional dependencies.
Although the participants felt the competition highlighted the team functional dependencies and other key team dynamics, the evaluators felt the challenge demonstrated a little less functional dependency.
Some topics covered: artificial clonal selection, biomedical data mining, cat swarm optimization, computational intelligence, fuzzy functional dependencies, hybrid evolutionary learning algorithms, and risk-management models.
The language to express functional dependencies and algorithms is proposed.
Functional dependencies, revealed in this study, may be used for the screening control and predictions of psychophysical potential of athletes.
Traditionally, functional dependencies and multivalued dependencies have been the basis for the axiomatic foundation underlying the development of the related decomposition algorithms.
Functional Dependencies Analysis: With this new feature, data profiling users can analyze and measure dependencies between several data fields.
The text includes a new chapter on the relational model and functional dependencies, expanded chapters on Enhanced Entity Relationship diagrams and reverse mapping, updated exercises, case studies, and a glossary.
Dependency Tracker - gives program and project managers the tools needed to manage functional dependencies within and across projects, providing visual cues to indicate when commitments have been satisfied.
We show how the XML normal form can be obtained for a class of XML schemas and a class of XML functional dependencies.

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