ads_back_count

insert into ads_back_count
select
    '2020-03-20',
    date_add(next_day('2020-03-20','MO'),-7),
    count(*)
from 
(
-- 找出本周活跃用户
select
    mid_id
from dwt_uv_topic
where login_date_last>=date_add(next_day('2020-03-20','MO'),-7)
and login_date_last<date_add(next_day('2020-03-20','MO'),-1)
-- 过滤掉在本周内进行两次登陆的用户
and login_date_first<date_add(next_day('2020-03-20','MO'),-7)
) current_wk

left join 
(
-- 找出上周活跃用户
select 
    mid_id
from dws_uv_detail_daycount
where dt<date_add(next_day('2020-03-20','MO'),-7)
and dt>=date_add(next_day('2020-03-20','MO'),-7*2)
group by mid_id
) last_wk
on current_wk.mid_id=last_wk.mid_id
where last_wk.mid_id is null;
-- left join 后 last_wk.mid_id 为null的就是回流用户