Quick Scan Report – Orphan Database Users
An orphan database user is reported by the Database Health Monitor when a user is found that does not have a linked corresponding SQL Login. This means that the user can’t login, and therefore can’t do anything with that database.
If you have an orphan user with the name of Steve, you can attempt to map that user to an active SQL Server login named Steve with the following command:
EXEC sp_change_users_login 'Update_One', 'Steve', 'Steve';