题解 | #未完成试卷数大于1的有效用户#

select uid, count(if(submit_time is null,1,null)) as incomplete_cnt, count(if(submit_time is null,null,1)) as complete_cnt, group_concat(distinct concat_ws(':',date(start_time),tag)separator';') as detail from exam_record inner join examination_info using(exam_id) where year(start_time)=2021 group by uid having complete_cnt >=1 and incomplete_cnt between 2 and 4 order by incomplete_cnt desc