The first layer of security when you open Microsoft Dynamics NAV is database security.
After you start Microsoft Dynamics NAV and attempt to open the database, your credentials are checked. If you have not been granted permission to open the database then the database is not listed in the Available Databases window. For more information about granting a user permission to create or work with a Microsoft Dynamics NAV database, see Setting Database Owner and Security Administration Permissions.
For more information about how to open a database, see How to: Open Databases.