【牛客】SQL125 得分不小于平均分的最低分

描述

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。

示例数据 exam_record表（uid用户ID, exam_id试卷ID, start_time开始作答时间, submit_time交卷时间, score得分）：

id	uid	exam_id	start_time	submit_time	score
1	1001	9001	2020-01-02 09:01:01	2020-01-02 09:21:01	80
2	1002	9001	2021-09-05 19:01:01	2021-09-05 19:40:01	89
3	1002	9002	2021-09-02 12:01:01	(NULL)	(NULL)
4	1002	9003	2021-09-01 12:01:01	(NULL)	(NULL)
5	1002	9001	2021-02-02 19:01:01	2021-02-02 19:30:01	87
6	1002	9002	2021-05-05 18:01:01	2021-05-05 18:59:02	90
7	1003	9002	2021-02-06 12:01:01	(NULL)	(NULL)
8	1003	9003	2021-09-07 10:01:01	2021-09-07 10:31:01	86
9	1004	9003	2021-09-06 12:01:01	(NULL)	(NULL)

examination_info表（exam_id试卷ID, tag试卷类别, difficulty试卷难度, duration考试时长, release_time发布时间）

id	exam_id	tag	difficulty	duration	release_time
1	9001	SQL	hard	60	2020-01-01 10:00:00
2	9002	SQL	easy	60	2020-02-01 10:00:00
3	9003	算法	medium	80	2020-08-02 10:00:00

示例输出数据：

min_score_over_avg

87

解释：试卷9001和9002为SQL类别，作答这两份试卷的得分有[80,89,87,90]，平均分为86.5，不小于平均分的最小分数为87

select min(score) from
exam_record left join examination_info using(exam_id)
where tag='SQL' and score is not null and
score>= (
    select avg(score) as avg_score from
    exam_record left join examination_info using(exam_id)
    where tag='SQL' and score is not null)