One or more columns (fields) in a relational database that can uniquely identify a row in the table. If there are two or more candidate keys, only one is selected as the "primary." See primary key.

One of the principles within relational theory is that each entity’s row or tuple be uniquely identifiable. This means the defined structure includes some combination of attributes whose populated ...

The column (field) in a relational database that uniquely identifies the row in the table. For example, account number is often a primary key. A "composite primary key" or "super key" is made up of ...