How to maintain Database User Permissions when copying the Database from One SQL Server to another(Either through backups or sp_detach). The reason is the login sid is different in the target server and as a result the database user is not able to map to the login existing in the target server. The only way I can correct this is through dropping and recreating the user's again and assign the permissions, or change the system catalog - sysusers to remap the login to the user in the database.
I do not wish to use the sp_addalias as it is available only for backward compatibility.
Is there a better way of doing this ?