python - MySQLdb的SQL语句问题

import MySQLdb
conn=MySQLdb.connect(host="localhost",user="root",passwd="",db="test",charset="utf8")
cursor = conn.cursor()

n = cursor.execute("select * from studentlist")
for row in cursor.fetchall():
    for r in row:
        print r
        

像这种select * from studentlist 可以直接查询

但是如果我要换为下面类似语句，就会出现错误。

SELECT
    student_statistics_day.stat_day AS `日期`,
    studentlist.`name` AS `姓名`,
    studentlist.phone AS `手机`,
    studentlist.class AS `班级`,
    student_statistics_day.online_time AS `上课时间`,
    student_statistics_day.level_name AS `级别`
FROM
studentlist
LEFT JOIN student_statistics_day ON studentlist.student_id = student_statistics_day.student_id
LEFT JOIN student_day ON student_statistics_day.student_id = student_day.student_id
WHERE
    student_statistics_day.level_name = "优秀"
OR student_statistics_day.level_name = "良好"
ORDER BY
    `studentlist` DESC