题解 | #浙江大学用户题目回答情况#

select qpd.device_id,qpd.question_id,qpd.result 
from question_practice_detail as qpd
inner join user_profile as up
on qpd.device_id = up.device_id 
and university = "浙江大学" 
order by qpd.question_id

#select qpd.device_id,qpd.question_id,qpd.result 
#from question_practice_detail as qpd 
#where qpd.device_id = (
#    select device_id from user_profile
#    where university = "浙江大学");

内连接中的where是过滤表1的 所以在这个inner join中不适用，直接在on那边就行，如果是更多表也是用on来对更多表进行对应条件查询，且left join 和 right join 也是一样的