SQL：过去 30 天的滚动总和（按组）答案

【问题标题】：SQL: Rolling sum in the last 30 days by groupsSQL：过去 30 天的滚动总和（按组）
【发布时间】：2016-10-27 23:21:09
【问题描述】：

我有一张如下表：

date, custid, sales
2015-01-01, 01, 100
2015-01-10, 01, 200
2015-02-05, 01, 300
2015-03-02, 01, 400
2015-03-03, 01, 500
2015-01-01, 02, 100
2015-01-10, 02, 200
2015-02-05, 02, 300
2015-03-02, 02, 400
2015-03-03, 02, 500
...

如何按日期和 custid 生成过去 30 天的滚动总销售额。

期望的输出是：

date, custid, running_30_day_sales
2015-01-01, 01, 100
2015-01-10, 01, 300 --(100+200)
2015-02-05, 01, 500 --(200+300)
2015-03-02, 01, 700 --(300+400)
2015-03-03, 01, 1200 -- (300+400+500)
2015-01-01, 02, 100
2015-01-10, 02, 300 --(100+200)
2015-02-05, 02, 500 --(200+300)
2015-03-02, 02, 700 --(300+400)
2015-03-03, 02, 1200 -- (300+400+500)

【问题讨论】：

标签： sql amazon-redshift

【解决方案1】：

这是使用self join 的一种方法。每个日期都与 datediff >0 且

select a1.custid, a1.dt, a1.sales+sum(coalesce(a2.sales,0)) total
from atable a1
left join atable a2 on a1.custid=a2.custid 
and datediff(day,a2.dt,a1.dt)<=30 and datediff(day,a2.dt,a1.dt)>0
group by a1.custid,a1.dt,a1.sales
order by 1,2

Sample Demo in Postgres

为了更好的理解，看一下self-join using的查询结果

select a1.*,a2.*
from atable a1
left join atable a2 on a1.custid=a2.custid 
and datediff(day,a1.dt,a2.dt)<=30 and datediff(day,a1.dt,a2.dt)>0

【讨论】：

【解决方案2】：

这里有一个使用累积和的技巧：

with t as (
      select custid, date, sales from atable
      union all
      select custid, date + interval '30 day', sales from atable
     )
select custid, date,
       sum(sum(sales)) over (partition by cust_id order by date rows between unbounded preceding and current row) as sales_30day
from t
group by custid, date;

【讨论】：

我认为这会生成不在表中的行。
嗨，戈登，感谢您的回复。你能加一点评论吗？此外，当我在 redshift 上运行查询时，出现错误“错误：42601：带有 ORDER BY 子句的聚合窗口函数需要框架子句”
@vip 。 . .是的，你是对的。这将具有值更改的所有日期。如果 OP 只想过滤原始数据中的日期，那么使用另一个连接就很容易了。

【解决方案3】：

你也可以使用窗口函数这样找到它

SELECT custid, dt::date,
            SUM(sales) OVER (partition by custid ORDER BY dt
                            RANGE BETWEEN '30 days' PRECEDING AND '2 days' Following) as  sum_of_sales
            MIN(sales) OVER (partition by custid ORDER BY dt::date
                            RANGE BETWEEN '30 days' PRECEDING AND CURRENT ROW) as  minimum,
            MAX(sales) OVER (partition by custid ORDER BY dt::date
                            RANGE BETWEEN '2 days' PRECEDING AND '2 days' Following) as  maximum
      FROM atable

【讨论】：