one primly key

You can have only one primary key, but that can consist of as many columns as you need to uniquely identify your rows. where P_Td and LastName are columns in your table. If you think you want more than one primary key, then the answer is "not really." You can have only one primary key.

Only one primary key can be created for each table

It is a unique identifier, such as a driver license number, telephone number (including area code), or vehicle identification number (VIN). A relational database must always have one and only one primary key. Primary keys typically appear as columns in relational database tables

While many developers and database administrators may work with primary keys everyday, it is a fascinating topic to ask oneself, “What exactly is a primary key and can (or should) a database table contain multiple