We have a login on the dev server which mirrors the login on the production server, but I can't get it to mapped to another db in the same server group on the dev. When I edit the properties of the login in 'User Mapping", I check the map to 2nd db, and I get the following error:
Create failed for User 'myLogin_name'. (Microsoft.SqlServer.Smo)
User, group, or role 'mylogin_name' already exists in the current database. (Microsoft SQL Server, Error: 15023)
I know that user exists as it was listed under that db's security, users.
sounds like that user exists in the database but is not sync'd to the login (sids don't match). That can happen when the database is restored from a different server.
see if the user exist by: use <database> select * from sysusers where name = 'mylogin_name'
if its there then sync the user to the login with: alter user [myLogin_name] with login = [myLogin_name]