ชมรมเทนนิสมีสมาชิกกี่คน?
How many members does the club "Tennis Club" has?
club = pd.DataFrame(columns=['clubid', 'clubname']); member_of_club = pd.DataFrame(columns=['clubid', 'stuid']); student = pd.DataFrame(columns=['stuid'])
member_of_club[member_of_club['clubid'].isin(club[club['clubname'] == 'Tennis Club']['clubid'])]['stuid'].count()