ค้นหาชื่อนักเรียนที่อาศัยอยู่ใน Smith Hall
Find the first name of students who are living in the Smith Hall.
df_student = pd.DataFrame(columns=['fname', 'stuid']); df_lives_in = pd.DataFrame(columns=['stuid', 'dormid']); df_dorm = pd.DataFrame(columns=['dormid', 'dorm_name'])
df_student.merge(df_lives_in, on='stuid').merge(df_dorm[df_dorm['dorm_name'] == 'Smith Hall'], on='dormid')['fname']