有2个表 学生表（Student） 成绩表（grade）
一、方法1 反向求解
可以从反面求解，只要有一门课程不满足条件，则该学生不再考虑 select distinct g.no from grade g where g.socre<80
然后在学生表中反向求解学生 ，条件为学号不在上面查询的集合中的
select t.name,t.no from student t where t.no not in (
select distinct g.no from grade g where g.socre<80)
二、方法2 使用having min（）与group by
select m.name from ( select t.name, t.no, g.class_no, g.socre
from student t
left join grade g
on g.no = t.no) m
group by m.name
having min(m.socre)>= 83
三、方法3 使用 not exist
select *
from student t
where t.no not in (select distinct a.no
from grade a
where not exists (select 1
from grade b
where b.socre < 80
and b.no = a.no))