比较经典的题目,在实际工作中运用挺多的。先要考虑符合每个人符合哪类条件的,在通过条件筛选人数。 方法一,if做法 select t.等级, count(学生编号) as "学生人数" from( select 学生编号, if(分数 between 86 and 100,"优秀",if(分数 between 71 and 85,"良好",if(分数 between 60 and 70 ,"及格","不及格"))) as 等级 from 学生分数表 ) as t group by t.等级 方法二...