SQL 服务器：移动平均计算

Question

我有一个脚本可以根据过去 3 个月计算移动平均值。

是否可以修改此移动平均线以仅显示第 4 个月的值？或者当我想根据 4 个月进行计算时，然后显示第 5 行的值，依此类推...

所以重点是仅当我有足够的数据进行计算时才显示那个月的值。

SELECT 
    [Brand], [month],
    CAST(SUM([Volume]) AS INT) AS [Volume (t)],
    AVG(CAST(SUM([Volume]) AS INT)) OVER (PARTITION BY [Brand]) AS [Average (t)],
    AVG(CAST(SUM([Volume]) AS INT)) OVER (PARTITION BY [Brand] ORDER BY [month] ROWS BETWEEN 3 PRECEDING AND 1 PRECEDING) AS [Moving Average (3)]
FROM 
    dw_lc_full_aggregated_1
WHERE   
    [year] = 2016 AND 
    [month] BETWEEN 1 AND 9 AND
    [Navision Source] = 'HU' AND
    [Brand] = 'xxxxxxx'
GROUP BY 
    [Brand], [month]

Answer 1

谢谢！我按如下方式解决了它：

SELECT  [Brand],
        [month],
        cast(sum([Volume]) AS INT) as [Volume (t)],
        AVG(cast(sum([Volume])AS INT)) OVER (PARTITION BY [Brand]) AS [Average (t)],

        CASE WHEN (Row_Number() OVER (ORDER BY [month]))>3
        THEN AVG(cast(sum([Volume])AS INT)) 
                    OVER (PARTITION BY [Brand] ORDER BY [month] ROWS BETWEEN 3 PRECEDING AND 1 PRECEDING) 
                    ELSE NULL END AS [Moving Average (3)]
............

SQL 服务器：移动平均计算

SQL Server : moving average calculation

sql-server

moving-average