นักเรียนชื่อ "เอริค ต่าย" อยู่กี่ชมรม?
How many clubs does the student named "Eric Tai" belong to?
df_student = pd.DataFrame(columns=['stuid', 'fname', 'lname']); df_member_of_club = pd.DataFrame(columns=['clubid', 'stuid']); df_club = pd.DataFrame(columns=['clubname', 'clubid'])
df_club.merge(df_member_of_club, on='clubid').merge(df_student, on='stuid').loc[(df_student['fname'] == 'Eric') & (df_student['lname'] == 'Tai'), 'clubname'].nunique()