Orphaned users after a restore

When you restore a database, you can be left in a state where some users are orphaned from the server (even if there is a login with the same name)

Within SQL Server, there is a quick fix.

Step 1 - Run this in the newly restored database and it will show all the orphaned users

EXEC sp_change_users_login 'Report'


Step 2 - Run this and will assign the user to a login name 

EXEC sp_change_users_login 'UPDATE_ONE','',''

so for example

EXEC sp_change_users_login 'UPDATE_ONE','testuser','testuser'

And that's it.