select er.uid as uid,count(distinct er.exam_id) as exam_cnt,count(distinct pr.submit_time,pr.question_id) as question_cnt from exam_record er left join practice_record pr on er.uid=pr.uid and year(er.submit_time)=2021 and year(pr.submit_time)=2021 where er.uid in( select er.uid from exam_record er l...