2-3作业重点挖掘用户SQL查询方式

问题
作业中 重点挖掘用户是如何获取数据的
解析
数据为 案例一数据，代码如下
select user_class,avg(recen_num) as r_avg,avg(buy_frenq) as f_avg from<br /> (sELECT c.user_id,user_class,recen_num,buy_frenq <br /> from <br /> (sELECT a.user_id,user_class,b.recen_num <br /> from RFM_inall a <br /> join r_clevel b <br /> on a.user_id = b.user_id<br /> ) c<br /> join f_clevel d <br /> on c.user_id = d.user_id <br /> group by c.user_id,user_class,recen_num,buy_frenq<br /> ) e <br /> group by user_class;