Fully-functional dependency in DBMS

An attribute is fully functional dependent on another attribute, if it is Functionally Dependent on that attribute and not on any of its proper subset.

For example, an attribute Q is fully functional dependent on another attribute P, if it is Functionally Dependent on P and not on any of the proper subset of P.

Let us see an example −

<ProjectCost>

<EmployeeProject>

The above relations states that −

Days are the number of days spent on the project.

However, it is not fully functional dependent.

Whereas the subset {EmpID, ProjectID} can easily determine the {Days} spent on the project by the employee.

This summarizes and gives our fully functional dependency −