Error when calculating a running total (cumulative over the previous periods)

问题

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)

Which would return something like:

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

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

I'm trying this:

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)

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.

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.

回答1:

"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

回答2:

Are you on 2005 or later, You can break this using a CTE

WITH CTE AS (
SELECT YEAR(MT.Created) as Yr 
    , MONTH(MT.Created) as Mth
    ,( 
    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 
FROM My_Table MT 
WHERE MT.Created > CAST('2009/01/01' AS datetime))

SELECT Yr, Mth, SUM(Total) as Total FROM CTE
GROUP BY Yr, Mth 
ORDER BY Yr, Mth

回答3:

You could take the aggregate out of the final query with something like this:

WITH CTE AS 
(SELECT DISTINCT YEAR(MT.Created) AS [Year]
    , MONTH(MT.Created) AS [Month]
FROM My_Table MT
WHERE MT.Created > CAST('2009/01/01' AS datetime)
)
SELECT MT.[Year]
    , MT.[Month]
    ,(
    SELECT COUNT(*) FROM My_Table MT_int
    WHERE MT_int.Created >= CAST('2009/01/01' AS datetime)
        AND (YEAR(MT_int.Created) < MT.[Year]
            OR (YEAR(MT_int.Created) = MT.[Year]
                AND MONTH(MT_int.Created) <= MT.[Month])
            )
        -- the last day of the current month
        -- (Additional conditions can go here)
    ) AS [Total added this month]
FROM CTE MT
ORDER BY MT.[Year], MT.[Month]

I think that should cover all the past orders in a previous year or a previous month in the same year along with all the orders in that month.

回答4:

Call it the slow way, but you could do it with a function. Don't do it if My_Table is big.

Create Function [dbo].[RunningTotal](@Yr int, @Mnth int)
 Returns int
AS
BEGIN
 Declare @RC int
 Select @RC=count(*)
 From My_Table
 Where Year(Created)<@Yr or (Year(Created)=@Yr and Month(Created) <= @Mnth)

 Return @RC
END

来源：https://stackoverflow.com/questions/4107479/error-when-calculating-a-running-total-cumulative-over-the-previous-periods

标签

sql

tsql

subquery

aggregate