题解 | #得分不小于平均分的最低分#

with
    tmp as (
        select
            exam_id,
            avg(er.score) as avg
        from
            exam_record er
            left join examination_info ei using (exam_id)
        where
            ei.tag = "SQL"
        group by
            exam_id
    )
select
    min(if (er.score >= tmp.avg, er.score, null)) as min_score_over_avg
from
    exam_record er
    left join tmp using (exam_id);