Not surprisingly, Windows authentication mode allows you to connect to the database using Windows authentication. By default SQL Server will only allow Windows authentication mode. SQL Server authentication mode allows you to connect to the database using an username and password.
To allow both modes of authentication do the following.
- Right-click on the server and pick the “Properties” menu option.
- Click on the “Security” page.
- Pick the “SQL Server and Windows Authentication mode” setting.
- Click the “OK” button.
You will need to restart SQL Server for the change to take effect.
For more information see: