class_id的最高分数很简单
select class_id, max(classScore) score from scoresgroup by class_id
如果您随后需要知道分数表中的哪些行具有最高分数，则可以进行联接。如果每个班级的平均分数不止一个，您可能会得到两行以上。
select id, class_id, classscore fromscores sinner join( select class_id, max(classScore) score from scores group by class_id)ton t.class_id = s.class_id and t.score = s.classScore
否则我可能会使用CTE
with maxScores as( select class_id, max(classScore) score from scores group by class_id)select id, class_id, classscore fromscores son maxScores.class_id = s.class_id and maxScores.score = s.classScore
