Developing a Conceptual Model › Normalizing Your Data Model › Functional Dependence

Functional Dependence

Functional dependence describes the relation between the key and non-key attributes of an entity. An attribute of an entity is functionally dependent on a key of that same entity if, for each value of the key, there is one and only one value of the non-key attribute.

The non-key attributes are functionally dependent on Supplier Number because there is only one precise corresponding value for Name, City and Postal Code for a particular value of Supplier Number.