题解 | #对比一周的播放完成率变化#

#纯小白思路
#还是先说下题意吧，不知道牛客花钱了，这题意说的云山雾绕的。
#求每周的变化率,(当前周几+1完播率-当前周几完播率)/当前周几完播率，公式反过来也行。（当前周几/当前周几-1）/当前周几-1
with tiaojian as (
select
weekday(start_time)+1 as weekth,
sum(case when timestampdiff(second,start_time,end_time)>=vb.time_len
then 1 else timestampdiff(second,start_time,end_time)/vb.time_len end)/count(distinct uid) as weekwbl
from  user_play_log_tb ub inner join
video_info_tb vb on  ub.vid=vb.vid
group by weekday(start_time)+1
order by weekth asc
)

select 
t.weekth,
concat(
round(
(
(last_weekwbl-weekwbl)/weekwbl)*100,1),"%") as play_ratio_delta
from(
select 
weekth,
weekwbl,
lead(weekwbl,1,(select weekwbl from tiaojian where weekth=1))over(order by weekth asc) as last_weekwbl
from tiaojian
) as t