多个时间段的滑动窗口平均值 - SQL Server

Question

我有一个 SQL 查询，它返回过去 30 天内注册的用户的平均注册时间：

select avg(datediff(dd, acquisitiontime,createdate))  from users where 
createdate > getdate() - 30 and
acquisitionmedium = 'cpc' and
acquisitionsource = 'google' and
acquisitiontime is not null

我想看看随着时间的推移这种情况如何变化。

如何更改此查询，以便我可以输出一个带有 (Month, Avg Time to Signup for that Month) 的表？

Answer 1

select
    DATEADD(month, -n.number, getdate()) OneMonthFromThisDate,
    avg(datediff(dd, acquisitiontime, createdate)) AverageInThisMonth
from users
join master..spt_values n on n.type='P' and n.number between 1 and 24
where createdate >  DATEADD(month, -n.number, getdate())
  and createdate <= DATEADD(month, 1-n.number, getdate())
  and acquisitionmedium = 'cpc'
  and acquisitionsource = 'google'
  and acquisitiontime is not null
group by n.number, DATEADD(month, -n.number, getdate())
order by n.number

这会将最新的放在首位。