可以只用两层嵌套select case when datediff(m,ma)>29 then '流失用户' when datediff(m,ma)>6 then '沉睡用户' when datediff(m,mi) <7 then '新晋用户' else '忠实用户' end as user_grade, round(count(uid)/max(sm),2) as ratio from( select uid, min(in_time) as mi, max(out_time) as ma, (select max(out_time) from tb_user_log) as m, (select count(distinct uid) from tb_user_log) as sm from tb_user_log group by 1) as t1 group by 1 order by 2 desc