题解 | #浙江大学用户题目回答情况#

#内连接查询
select user_profile.device_id, question_practice_detail.question_id, question_practice_detail.result 
from user_profile inner join question_practice_detail 
on question_practice_detail.device_id = user_profile.device_id
where user_profile.university = '浙江大学'
order by question_practice_detail.question_id

#连接查询
select question_practice_detail.device_id, question_practice_detail.question_id, question_practice_detail.result 
from user_profile,question_practice_detail
where user_profile.device_id = question_practice_detail.device_id
and user_profile.university = '浙江大学'

#子查询
select device_id, question_id, result from question_practice_detail 
where device_id = 
(select device_id from user_profile where university='浙江大学' )