Which city has most number of customers?
select t2.city from customers as t1 join addresses as t2 on t1.customer_address_id = t2.address_id group by t2.city order by count ( * ) desc limit 1
How many customers does it have?
select count ( * ) from customers as t1 join addresses as t2 on t1.customer_address_id = t2.address_id group by t2.city order by count ( * ) desc limit 1
Give me the names of those customers
select t1.first_name, t1.last_name from customers as t1 join addresses as t2 on t2.address_id = t1.customer_address_id where t2.city = ( select t2.city from customers as t1 join addresses as t2 on t1.customer_address_id = t2.address_id group by t2.city order by count ( * ) desc limit 1 )