functional dependency

(redirected from Functional dependencies)

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 ?
There are also interfaces with ancillary control devices which have resulted in numerous functional dependencies and interconnections.
A microservice is a well-encapsulated component that can function without external functional dependencies and handles all the details regarding its own operational data storage and transactions.
Those who believe that not naming a column well and clearly, or not seeing to it that data structures are based on proper functional dependencies, are not saying they do not have time to do that work, they are saying they really do not understand how to do that work.
Our system extracts the super key, candidate key and functional dependencies from the student answer table based on the training data.
Functional Dependencies and###designed for RDBMS namely select, project, join,
denote attributes; X, Y and Z denote set of attributes, and F a set of functional dependencies.
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.
Petit method is the only method to extract functional dependencies from DDL code and program code, MeRCI method is the only method to elicit redundancy from DDL code and program code.
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.
Methods for testing web services should cover test scenarios that include and test the discovery of the web service, the data formats exchanged between the services, the request/response mechanisms, the invocation sequences, hierarchical functional dependencies amongst web services and input/output dependency between web services.

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