计算每个月过去 12 个月的平均值？

Posted 2023-03-31

【中文标题】计算每个月过去 12 个月的平均值？

【英文标题】：Calculate the average of the last 12 months for every month?

【发布时间】：2020-03-27 09:12:15

【问题描述】：

我有一个带有值的 SQL 服务器表：

 CREATE TABLE [dbo].[MonthleyAvarage](
    [Boxes] [int] NULL,
    [DateMonthly] [date] NULL
) ON [PRIMARY]
GO

insert into MonthleyAvarage ([Boxes],[DateMonthly]) values (1,'01/01/2010')
insert into MonthleyAvarage ([Boxes],[DateMonthly]) values (10,'02/01/2010')
insert into MonthleyAvarage ([Boxes],[DateMonthly]) values (5,'03/01/2010')
insert into MonthleyAvarage ([Boxes],[DateMonthly]) values (9,'04/01/2010')
insert into MonthleyAvarage ([Boxes],[DateMonthly]) values (3,'05/01/2010')
insert into MonthleyAvarage ([Boxes],[DateMonthly]) values (7,'06/01/2010')
insert into MonthleyAvarage ([Boxes],[DateMonthly]) values (5,'07/01/2010')
insert into MonthleyAvarage ([Boxes],[DateMonthly]) values (4,'08/01/2010')
insert into MonthleyAvarage ([Boxes],[DateMonthly]) values (55,'09/01/2010')
insert into MonthleyAvarage ([Boxes],[DateMonthly]) values (6,'10/01/2010')
insert into MonthleyAvarage ([Boxes],[DateMonthly]) values (8,'11/01/2010')
insert into MonthleyAvarage ([Boxes],[DateMonthly]) values (0,'12/01/2010')
insert into MonthleyAvarage ([Boxes],[DateMonthly]) values (2,'01/01/2011')
insert into MonthleyAvarage ([Boxes],[DateMonthly]) values (1,'02/01/2011')

我试图计算每个月过去 12 个月的平均值，但我只计算了过去 12 个月的累积平均值

select AVG(Boxes) over (order by DATEADD(MONTH, DATEDIFF(MONTH, 0, DateMonthly), -12)) as avarage,DateMonthly,Boxes 
from monthleyavarage

我怎样才能只用过去 12 个月？变成这样：

请问我该怎么做？

【参考方案1】：

您可以使用带有适当窗口子句的窗口函数：

select 
    boxes,
    dateMonthly,
    avg(boxes) 
        over(order by dateMonthly rows between 11 preceding and current row) avg_boxes
from monthleyavarage

这会为您提供当月和前 11 个月的平均值。