SQL (Orphaned) User Without a Login: HowTo Create a Login For The User

Whenever I restore a database from a customer in my development environment I have the issue of orphaned users: users in the database have no corresponding login on the server/instance.
I found this nice answer on SO that uses the sp_change_users_login stored procedure for this.
You can use sp_change_users_login to create a login for users already in the database.

USE databasename                      -- The database I recently attached
EXEC sp_change_users_login 'Report'   -- Display orphaned users
EXEC sp_change_users_login 'Auto_Fix', 'UserName', NULL, 'Password'

You get the UserName(s) from the sproc when you run it with @Action='Report'.