Definition: In order to be in Second Normal Form, a relation must first fulfill the requirements to be in First Normal Form.  Additionally, each nonkey attribute in the relation must be functionally dependent upon the primary key.

Example:The following relation is in First Normal Form, but not Second Normal Form:

In the table above, the order number serves as the primary key.  Notice that  the customer and total amount are dependent upon the order number -- this data is specific to each order.  However, the contact person is dependent upon the customer.  An alternative way to accomplish this would be to create two tables:

The creation of two separate tables eliminates the dependency problem experienced in the previous case.  In the first table, contact person is dependent upon the primary key -- customer name.  The second table only includes the information unique to each order.