แสดงชื่อโทรศัพท์ที่อยู่ในตลาดพร้อมจำนวนร้านค้ามากกว่า 50 แห่ง
Show the names of phones that are on market with number of shops greater than 50.
df_market = pd.DataFrame(columns=['Market_ID', 'Num_of_shops']); df_phone = pd.DataFrame(columns=['Name', 'Phone_ID']); df_phone_market = pd.DataFrame(columns=['Market_ID', 'Phone_ID'])
df_phone[df_phone['Phone_ID'].isin(df_phone_market[df_phone_market['Market_ID'].isin(df_market[df_market['Num_of_shops']>50]['Market_ID'])]['Phone_ID'])]['Name']