ช่องที่ออกอากาศทั้งเช้าและกลางคืนชื่ออะไร?
what are the names of the channels that broadcast in both morning and night?
df_channel = pd.DataFrame(columns=['name', 'channel_id']); df_broadcast = pd.DataFrame(columns=['channel_id', 'time_of_day'])
df_channel.merge(df_broadcast[df_broadcast['time_of_day'] == 'Morning'], on='channel_id').merge(df_broadcast[df_broadcast['time_of_day'] == 'Night'], on='channel_id')['name']