DBMS Transitive dependency

A functional dependency is said to be transitive if it is indirectly formed by two functional dependencies. For e.g.

X -> Z is a transitive dependency if the following three functional dependencies hold true:
X->Y
Y does not ->X
Y->Z

Note: A transitive dependency can only occur in a relation of three of more attributes. This dependency helps us normalizing the database in 3NF (3rd Normal Form).

Example: Let's take an example to understand it better:



{Book} ->{Author} (if we know the book, we knows the author name)
{Author} does not ->{Book}
{Author} -> {Author_age}
Therefore as per the rule of transitive dependency: {Book} -> {Author_age} should hold, that makes sense because if we know the book name we can know the author's age.