[大厂真题]SQL27题解 | 查询成绩
# 成绩，关联学生，课程
# 找出平均成绩
SELECT count(*)
from (
SELECT a.sId,avg(a.score) as avg_score
FROM SC a
left join Course b
on a.cId=b.cId # 关联字段
left join Student c
on a.sId=c.sId
where b.cname in ('语文','数学','英文') #名称
group by a.sId
having avg(a.score)>60
) t