#提交时返回了一个none值，后来发现是不小于忘记取等了，导致等于的这种情况就没有值，变成了none select min(score) min_score_over_avg from exam_record er join examination_info ei on er.exam_id = ei.exam_id where ei.tag = 'SQL' and score >= (select avg(score) from exam_record e1 join examination_info e2 on e1.exam_id = e2.exam_id where e2.tag = 'SQL')