Context: CREATE TABLE phone_market (Num_of_stock INTEGER, Phone_ID VARCHAR); CREATE TABLE phone (Name VARCHAR, Phone_ID VARCHAR)
Question: For each phone, show its names and total number of stocks.
Answer: SELECT T2.Name, SUM(T1.Num_of_stock) FROM phone_market AS T1 JOIN phone AS T2 ON T1.Phone_ID = T2.Phone_ID GROUP BY T2.Name