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

Show the proportion of the districts of markets they are on, a pie chart.
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" 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"