Please list the headquarters of the store that is called Blackville?
select t3.headquartered_city from store as t1 join store_district as t2 on t1.store_id = t2.store_id join district as t3 on t2.district_id = t3.district_id where t1.store_name = "Blackville"
What is the population of that city?
select t3.city_population from store as t1 join store_district as t2 on t1.store_id = t2.store_id join district as t3 on t2.district_id = t3.district_id where t1.store_name = "Blackville"
What is the name of the store in the city with the greatest population?
select t1.store_name from store as t1 join store_district as t2 on t1.store_id = t2.store_id join district as t3 on t2.district_id = t3.district_id order by t3.city_population desc limit 1