what are the districts that have city mall.
SELECT t3.District_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 WHERE t1.Type   =   "City Mall"
districts with city mall refers to filtering stores by Type = 'City Mall' and joining with districts through an intermediary store_district table to get District_name;