A functional dependency is a relationship between two attributes. Typically between the PK and other non-key attributes with in the table. For any relation R, attribute Y is functionally dependent on attribute X (usually the PK), if for every valid instance of X, that value of X uniquely determines the value of Y.
X ———–> Y
The left-hand side of the FD is called the determinant, and the right-hand side is the dependent.
SIN ———-> Name, Address, Birthdate
SIN determines names and address and birthdays. Given SIN, we can determine any of the other at tributes within the table.
Sin, Course ———> DateCompleted
Sin and Course determine date completed. This must also work for a composite PK.
ISBN ———–> Title
ISBN determines title.