SQL SUM OVER PARTITION BY Calculate % of group

Question

Can anyone tell me why the below won't compile?

I'm trying to calculate what % the 'M3' marked transaction is of the whole batch.

I think it would be easy enough if there was only ever one batch, but sometimes there will be multiple.

Whole code is below:

SELECT 
    [Batch],
    [DocNum],
    [Date],
    [Time],
    [Location],
    [ItemCode],
    [Brand],
    [Quantity],
    CASE
        WHEN [Variance] IS NULL
            THEN ''
        ELSE [Variance]
    END AS [Variance],
    CASE
        WHEN [Comments] IS NULL
            THEN ''
        ELSE [Comments]
    END AS [Comments],
    CASE
        WHEN [Variance] = 'M3'
            THEN(
                (
                (SELECT
                    ABS([Quantity])
                  FROM #BatchReport
                  WHERE [Variance] = 'M3')
                 / 
                 (SELECT
                     SUM([Quantity])
                     FROM #BatchReport
                     WHERE [Quantity] > 0)
                ) * 100) OVER (PARTITION BY [Batch])
        ELSE '0'
    END AS [Pct Loss],                          
    SUM([Quantity]) OVER (PARTITION BY [Batch]) AS [Difference],
    ((SUM([Quantity]) - MAX([Quantity])) * 100) / MAX([Quantity]) OVER (PARTITION BY [Batch]) AS [Pct Difference]


FROM #BatchReport
WHERE [DocNum] IS NOT NULL
GROUP BY [Batch], [DocNum], [Date], [Time], [Variance], [Brand], [Comments], [Quantity], [Location], [ItemCode]
ORDER BY [Batch], [Date], [Time]

Error text: Incorrect syntax near the keyword 'OVER'.

The error vanishes if I remove this part:

CASE
        WHEN [Variance] = 'M3'
            THEN(
                (
                (SELECT
                    ABS([Quantity])
                  FROM #BatchReport
                  WHERE [Variance] = 'M3')
                 / 
                 (SELECT
                     SUM([Quantity])
                     FROM #BatchReport
                     WHERE [Quantity] > 0)
                ) * 100) OVER (PARTITION BY [Batch])
        ELSE '0'
    END AS [Pct Loss]

Sample of something like what I'm trying to get:

Thanks!

Answer 1

Your expression logic is basically incomprehensible. I am guessing you want some sort of ratio between "M3" values and overall values. My best guess is:

(100.0 * SUM(CASE WHEN [Variance] = 'M3' THEN ABS([Quantity]) END) /
 SUM(CASE WHEN Quantity > 0 THEN Quantity END ) OVER (PARTITION BY Batch)
) as [Pct Loss]

However, your GROUP BY is so complex, that I would be surprised if your query did what you want. I think you should post another question with sample data and desired results.