In database design, a primary key is important because it serves as a unique identifier for a row of data in a database table. A primary key makes it convenient for a user to add, sort, modify or delete data in a database.
One of the critical steps in database programming is the inclusion of a primary key to a database table. This ensures that each record in the table is distinct from other records, which eliminates the possibility of duplicate data. A primary key is composed of one or several column fields. Once a primary key is added to a table, it should remain constant and should not deviate from its purpose, which is to identify a database record.