List the name of all different customers who have some loan sorted by their total loan amount.
return customers ;return different #1 ;return names of  #2 ;return loans of  #2 ;return loan  amounts of  #4 ;return sum of  #5 for each  #2 ;return #3 sorted by #6
['select', 'project', 'project', 'project', 'project', 'group', 'sort']