题解 | #统计复旦用户8月练题情况#

# 1.筛选学校、月份
# 2. 计算问题汇总还有回答正确的汇总

select up.device_id, '复旦大学' as university,
  count(question_id) as question_cnt,
  sum(if(qpd.result = 'right', 1, 0)) as right_question_cnt
from user_profile as up
left join question_practice_detail as qpd
on qpd.device_id = up.device_id and month(qpd.date) = 8
where up.university = '复旦大学'
group by up.device_id