子查询 select a.exam_id exam_id,count(distinct b.uid) uv,round(avg(b.score),1) avg_score from examination_info a join exam_record b on a.exam_id=b.exam_id and a.tag='SQL' where b.uid in (select uid from user_info where level >5) and left(a.release_time,10)=left(b.start_time,10) group by left(b.star...
