计算用户留存率:
怎么计算留存率?

sql代码(HUE上运行):
SELECT
a.dt1 `创作日期`,
a.cnt `创作用户量`,
concat((round((a.cnt1/a.cnt)*100, 2)), '%') `次日首页留存率`,
concat((round((a.cnt2/a.cnt)*100, 2)), '%') `3日首页留存率`,
concat((round((a.cnt3/a.cnt)*100, 2)), '%') `7日首页留存率`
from (
SELECT t1.dt1,
count(distinct if(datediff(t2.dt2,t1.dt1)=0,t2.device_id,null)) cnt,
count(distinct if(datediff(t2.dt2,t1.dt1)=1,t2.device_id,null)) cnt1,
count(distinct if(datediff(t2.dt2,t1.dt1)=3,t2.device_id,null)) cnt2,
count(distinct if(datediff(t2.dt2,t1.dt1)=7,t2.device_id,null)) cnt3
FROM
(SELECT dt dt1,
device_id
FROM dws_zdm.dws_zdm_hive_traffic_home_feed_h
WHERE dt BETWEEN '${start_date}' AND'${end_date}'