question: List the name of all different customers who have some loan sorted by their total loan amount.
#1 return customers 
#2 return different #1 
#3 return names of  #2 
#4 return loans of  #2 
#5 return loan  amounts of  #4 
#6 return sum of  #5 for each  #2 
#7 return #3 sorted by #6