题解 | #查询结果去重#
浙江大学用户题目回答情况
http://www.nowcoder.com/practice/55f3d94c3f4d47b69833b335867c06c1
解法一:内连接
SELECT q.device_id,q.question_id,q.result
FROM question_practice_detail as q INNER JOIN user_profile as u ON q.device_id = u.device_id
WHERE u.university = "浙江大学"
解法二:子查询
SELECT device_id,question_id,result
FROM question_practice_detail as q
WHERE q.device_id in (SELECT u.device_id
FROM user_profile as u
WHERE u.university = "浙江大学")