แสดงรายชื่อผู้เล่นที่ได้รับการฝึกสอนโดยโค้ชอันดับ 1
Show the names of players coached by the rank 1 coach.
df_player = pd.DataFrame(columns=['Player_name', 'Player_ID']); df_coach = pd.DataFrame(columns=['Coach_ID', 'Rank']); df_player_coach = pd.DataFrame(columns=['Coach_ID', 'Player_ID'])
df_player_coach[df_player_coach['Coach_ID'].isin(df_coach[df_coach['Rank'] == '1']['Coach_ID'])].merge(df_player, on='Player_ID')['Player_name']