CREATE TABLE phone (Name CLOB, Phone_ID NUMBER, Memory_in_G NUMBER, Carrier CLOB, Price FLOAT)
CREATE TABLE market (Market_ID NUMBER, District CLOB, Num_of_employees NUMBER, Num_of_shops FLOAT, Ranking NUMBER)
CREATE TABLE phone_market (Market_ID NUMBER, Phone_ID CLOB, Num_of_stock NUMBER)

I want to know the number of districts of markets they are on.
SELECT District, COUNT(District) FROM phone_market AS T1 JOIN market AS T2 ON T1.Market_ID = T2.Market_ID JOIN phone AS T3 ON T1.Phone_ID = T3.Phone_ID GROUP BY District
SELECT "District", COUNT("District") FROM "phone_market" "T1" JOIN "market" "T2" ON "T1"."Market_ID" = "T2"."Market_ID" JOIN "phone" "T3" ON "T1"."Phone_ID" = "T3"."Phone_ID" GROUP BY "District"