Concept of Transitive Functional Dependency

Tag: normalization , rdbms , database-normalization , transitive-dependency Author: twt1645 Date: 2014-04-03

Transitive functional dependency is defined as:

If A ? B and B ? C then A ? C (Reference: This Tutorial!)

If an attribute is dependent on a composite of two attributes ( i.e. A,B -> C), then is this a functional dependency?

Can we consider this type of dependence to be (or not) a transitive dependency?

Other Answer1

When an attribute is dependent on two or more determinants, it has a partial dependency on each of them.

In your example, C has a partial dependency on A and a partial dependency on B.

Partial and transitive dependency are not related concepts. You can have a dependency which is either partial, or transitive or both. A transitive dependency occurs when you have a non-key predicate that is placed in a "child" relation when it properly belongs in the "parent" relation.


To answer the OP's first question, yes, AB->C is a functional dependency.