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 ...

A primary key is a field used to uniquely identify every record in the database. Sometimes primary keys are obvious, for example a car license plate could be used to uniquely identify cars.

The superiority of surrogate versus natural keys is a hotly debated topic among database developers. Susan Harkins offers some insights into when -- and why -- you might choose one over the other.

Duplicate and Ignore on MySQL Inserts. MySQL table primary keys and unique indexes prevent multiple rows with the same index from being added to the table. If you try to insert a duplicate row ...