题解 | #得分不小于平均分的最低分#

select min(IF(er.score >= (select avg(er.score) as avg
                      from exam_record er
                               left join examination_info ei on er.exam_id = ei.exam_id
                      where ei.tag = 'SQL'
                        and er.score is not null
                      group by ei.tag), er.score, 1000)) as min_score_over_avg
from exam_record er
         left join examination_info ei on er.exam_id = ei.exam_id
where ei.tag = 'SQL'
  and er.score is not null;