Friday, 9 December 2016

What is functional dependency in dbms

What is functional dependency in DBMS? / Define Functional dependency / How to write a functional dependency? / Functional dependency examples

Functional Dependency

Functional Dependency is the property which verifies the relationship between two attributes / two sets of attributes. It means, determination of the value(s) of one attribute (or one set of attributes) using the other (or other set of attributes). This property is helping us in designing a good database.
A FD can be written as A  B. This can be read as "A determines the value of B" or "value of B can be uniquely determined by A". 

For example, if you know the register number of a student you would easily identify other details of that particular student. hence, all the other attributes of student table like name, branch, gender, dob etc. are all dependent on the register number attribute. In other words, register number determines all the other attributes uniquely.

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