Full Functional Dependency(FFD)

Full Functional Dependency(FFD)

A functional dependency A-> B in relation schema R is fully functional dependency if B is not functionally dependent on any subset of A.

Full dependency between database attributes helps ensure data integrity and avoid data anomalies.

Example:

full function dependency example

 

If custid or ano is removed from the primary key access_date cannot be determined uniquely. So access_date is fully functional dependent on custid and ano .

But balance and bname depend only on the ano . If custid is removed from the primary key even then dependency of balance and bname on ano holds.

So balance and bname do not fully functionally dependent on primary key i.e. custid and ano.In other word balance and bname partially depend on primary key.

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