题解 | #得分不小于平均分的最低分#

-- 得分不小于平均分的最低分
-- 请从试卷作答记录表中找到SQL试卷得分不小于该类试卷平均得分的用户最低得分
-- 1.先筛选出得分不为空的选项
-- 2.然后通过avg()或者是sum() / count()求平均分
-- 3.从小于平均分中的选项中通过min()求出最低分
-- 4.使用内连接插叙SQL类型的考试
select
    min(score) as min_score_over_avg
from
    exam_record
    join examination_info using (exam_id)
where
    tag = 'SQL'
    and score >= (
        select
            sum(score) / count(score)
        from
            exam_record
            join examination_info using (exam_id)
        where
            tag = 'SQL'
            and score is not null
    )