Manage a database
Add a primary key to a table
Create a primary key to associate data between multiple tables.
In the Navigation Pane, right click a table, and select Design View.
Select the field or fields you want to use as the primary key.
Select Design > Primary Key.
For more info, see Add or change a primary key.
Backup your database
Select File > Save As.
Under Database File Types, select Save Database As.
Under Advanced, select Back Up Database and then select Save As.
The default file name includes the source database and when the backup occurred.