题解 | #每个用户的第一有效信息#
每个用户的第一有效信息
https://www.nowcoder.com/practice/4408f866778b44c5bcebf17c386d7d13
select device_id , case when answer_cnt then concat('答题数:',answer_cnt) when gpa then concat('gpa:',gpa) when age then concat('年龄:',age) else '暂无关键信息' end as key_info from user_profile order by device_id;