Aug 29, 2017

Database second normal form - all nonkey columns must depend on the entire primary key.

Second normal form and composite keys.
Second normal form is a special-case normal form that has to do with tables that have composite primary keys. A composite primary key includes two or more columns.

In second normal form, all nonkey columns must depend on the entire primary key. In other words, any nonkey columns added to a table with a composite primary key cannot be dependent on only part of the primary key.