Which cities have customer_type_code of "Good Credit Rating"?
select distinct town_city from customers where customer_type_code = "Good credit Rating"
Which ones do not?
select distinct town_city from customers where customer_type_code != "Good credit Rating"
Give the counts of the town city groups of customers in that first query.
select town_city, count(*) from customers where customer_type_code = "Good credit Rating" group by town_city
Just return the town city with the least number.
select town_city from customers where customer_type_code = "Good credit Rating" group by town_city order by count(*) limit 1