SQL21 Zhejiang University User Question Answer Description Title: Now the operation wants to check the details of all user question answers from Zhejiang University, please take out the corresponding data

 Approach 1: Screen directly from Cartesian product

select a.device_id,question_id,result 
from question_practice_detail a, user_profile b 
where a.device_id=b.device_id and university="浙江大学";

Method 2: Recursive subquery

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

Method 3: inner join

select a.device_id,question_id,result 
from question_practice_detail a inner JOIN user_profile b
on a.device_id=b.device_id
where university = "浙江大学"