A PRIMARY KEY constraint in SQL Server is a field or column which ensures that each entry in a table is must be unique and not null.
A primary key can be created at the column or table level. The following is an example to illustrate this:
![Primary Key Constraint in SQL Server](https://www.shekhali.com/wp-content/uploads/2020/06/Primary-key-in-SQL-Server-2.png)
A PRIMARY KEY constraint in SQL Server is a field or column which ensures that each entry in a table is must be unique and not null.
A primary key can be created at the column or table level. The following is an example to illustrate this: