题解 | #得分不小于平均分的最低分#

    min(score)  min_score_over_avg 
from exam_record
join examination_info using(exam_id)
where tag='SQL' and score >=  -- 筛选试卷类别为tag，且分数大于平均分 ，然后去最小的分数即可
(
    select avg(score)
    from exam_record
    join examination_info using(exam_id)
   where tag='SQL'
)