-- Database schema
| phone : Name [ TEXT ] , Phone_ID [ INT ] primary_key , Memory_in_G [ INT ] , Carrier [ TEXT ] , Price [ INT ] | market : Market_ID [ INT ] primary_key , District [ TEXT ] , Num_of_employees [ INT ] , Num_of_shops [ INT ] , Ranking [ INT ] | phone_market : Market_ID [ INT ] primary_key phone_market.Market_ID = market.Market_ID , Phone_ID [ TEXT ] phone_market.Phone_ID = phone.Phone_ID , Num_of_stock [ INT ] |
-- -- Show the names of phones that are on market with number of shops greater than 50.

SELECT T3.Name 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 WHERE T2.Num_of_shops  >  50;