Advantages of Primary Key in a Table in SQL Server

Hi George616,

A primary key is a single field or combination of fields that uniquely defines a record. None of the fields that are part of the primary key can contain a null value.

The PRIMARY KEY constraint uniquely identifies each record in a table.

Primary keys must contain UNIQUE values and can not contain NULL values.

A table can have only ONE primary key and in the table this primary key can consist of single or multiple columns (fields).

https://www.w3schools.com/sql/sql_primarykey.ASP