计算运行总计时的错误（前几个期间的累计） [英] Error when calculating a running total (cumulative over the previous periods)

问题描述

我有一个表，我们称它为 My_Table ，其中有一个 Created datetime列（在SQL Server中），我正在尝试获取一份报告，该报告历史上显示了在特定时间内每月在 My_Table 中有多少行。现在我知道我可以显示每个月有 个添加了：

I have a table, let's call it My_Table that has a Created datetime column (in SQL Server) that I'm trying to pull a report that shows historically how many rows were to My_Table by month over a particular time. Now I know that I can show how many were added each month with:

SELECT YEAR(MT.Created), MONTH(MT.Created), COUNT(*) AS [Total Added]
FROM My_Table MT
GROUP BY YEAR(MT.Created), MONTH(MT.Created)
ORDER BY YEAR(MT.Created), MONTH(MT.Created)

返回以下内容：

YEAR    MONTH     Total Added
-----------------------------
2009    01        25
2009    02        127
2009    03        241

但是，我想获取给定时间段内 total 的列表大小（称其为您想要的；运行总计，累计总和，历史报告）：

However, I want to get the total list size over the given period (call it what you will; a running total, a cumulative sum, a historical report):

   YEAR    MONTH     Total Size
   -----------------------------
-- 2008    12        325
   2009    01        350
   2009    02        477
   2009    03        718

我正在尝试：

SELECT YEAR(MT.Created)
    , MONTH(MT.Created)
    ,(
    SELECT COUNT(*) FROM My_Table MT_int
    WHERE MT_int.Created BETWEEN 
        CAST('2009/01/01' AS datetime)
        AND DATEADD(s,-1,DATEADD(mm, DATEDIFF(m,0,MT.Created)+1,0))
        -- the last day of the current month
        -- (Additional conditions can go here)
    ) AS [Total added this month]
FROM My_Table MT
WHERE MT.Created > CAST('2009/01/01' AS datetime)
GROUP BY YEAR(MT.Created), MONTH(MT.Created)
ORDER BY YEAR(MT.Created), MONTH(MT.Created)

但是，SQL Server响应此错误：

However, SQL Server is responding with this error:

Msg 8120, Level 16, State 1, Line 1
Column 'My_Table .Created' is invalid in the select list because 
it is not contained in either an aggregate function or the GROUP BY clause.

我只是知道，但我遗漏了一些明显的东西，但在走开之后回来盯着它看了一会儿，我很茫然。因此，如果有人愿意指出地球上的内容，而我在这里不见了（或指出一种更好的方法），我将永远感激不已。

I just know I'm missing something obvious, but after walking away and coming back and staring at it for a while I'm at a loss. So if someone would be so kind as to point out what on earth I'm missing here (or point me at a better way of doing it) I'd be eternally grateful.

推荐答案

正在运行表示一行一行。因此，一种方法是将前几个月的总和添加到当前月份。要处理年份界限，您还需要每个组的最小/最大日期。交叉应用有点RBAR，但是可以清楚地知道（发生了什么情况。）。

"Running" implies row by row. So one way is to sum previous months and add it to current month. To deal with year boundaries, you also take min/max date per group. The CROSS APPLY is slightly RBAR but makes it clear(er?) what is happening.

;WITH cTE AS
(
SELECT
     MIN(Created) AS FirstPerGroup,
     MAX(Created) AS LastPerGroup,
     YEAR(MT.Created) AS yr, MONTH(MT.Created) AS mth, COUNT(*) AS [Monthly Total Added]
FROM MY_Table MT
GROUP BY YEAR(MT.Created), MONTH(MT.Created)
)
SELECT
   C1.yr, c1.mth, SUM(C1.[Monthly Total Added]),
   ISNULL(PreviousTotal, 0) + SUM(C1.[Monthly Total Added]) AS RunningTotal
FROM
 cTE c1
 CROSS APPLY
 (SELECT SUM([Monthly Total Added]) AS PreviousTotal FROM cTE c2 WHERE c2.LastPerGroup < C1.FirstPerGroup) foo
GROUP BY
  C1.yr, c1.mth, PreviousTotal
ORDER BY
   C1.yr, c1.mth

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