1.secect 学号,count(课程号) 课程门数
from 表
group by 学号
having count(课程号)>=3
order by 课程门数 desc
2.secect 课程号,avg(成绩) 平均成绩
from 表
group by 课程号
order by 平均成绩
from 表
group by 学号
having count(课程号)>=3
order by 课程门数 desc
2.secect 课程号,avg(成绩) 平均成绩
from 表
group by 课程号
order by 平均成绩
明显是作业,呵呵
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还没有说明表结构!
from 学生表
where add_months(入学时间,12)<=SYSDATE