题解 | 查询成绩

select
    count(*)
from
    (
        select
            sname,
            avg(score) 平均分
        from
            test.Student st
            join test.SC sc on st.sId = sc.sId
            join test.Course co on sc.cId = co.cId
        group by
            sname
        having
            avg(score) > 60
    ) a