สมาชิกชมรม "Bootup Baltimore" อายุน้อยกว่า 18 ปีมีกี่คน?
How many members of club "Bootup Baltimore" are younger than 18?
df_club = pd.DataFrame(columns=['clubid', 'clubname']); df_student = pd.DataFrame(columns=['stuid', 'age']); df_member_of_club = pd.DataFrame(columns=['clubid', 'stuid'])
df_club.merge(df_member_of_club, on='clubid').merge(df_student, on='stuid').loc[(df_club['clubname'] == 'Bootup Baltimore') & (df_student['age'] < 18)].shape[0]