CREATE TABLE district (headquartered_city VARCHAR2, district_id VARCHAR2)
CREATE TABLE store_district (store_id VARCHAR2, district_id VARCHAR2)
CREATE TABLE store (store_id VARCHAR2)

Find the city with the most number of stores.
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 GROUP BY t3.headquartered_city ORDER BY COUNT(*) DESC LIMIT 1
SELECT "t3"."headquartered_city" FROM "store" "t1" JOIN "store_district" "t2" ON "t1"."store_id" = "t2"."store_id" JOIN "district" "t3" ON "t2"."district_id" = "t3"."district_id" GROUP BY "t3"."headquartered_city" ORDER BY COUNT(*) DESC FETCH FIRST 1 ROWS ONLY