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How to count active jobs at the end of each month across a period of time

  • May 19, 2013 at 6:19 pm

    #277917

    My apologies if this question has been answered elsewhere but I can’t find a solution. I need to count the number of active jobs that exist at the end of each month. A job is active if it has been received but not yet finished. The data looks like this:

    CREATE TABLE #Files

    (Job NVARCHAR(10), Received DATETIME, Finished DATETIME)

    INSERT INTO #Files (JOB, Received, Finished)

    SELECT 'A1', CAST('20120110' AS DATETIME), CAST('20120506' AS DATETIME) UNION ALL

    SELECT 'A23', CAST('20120113' AS DATETIME), NULL UNION ALL

    SELECT 'B4', CAST('20120221' AS DATETIME), CAST('20120224' AS DATETIME) UNION ALL

    SELECT 'L5', CAST('20120307' AS DATETIME), CAST('20120425' AS DATETIME) UNION ALL

    SELECT 'D5', CAST('20120316' AS DATETIME), NULL UNION ALL

    SELECT 'S3', CAST('20120323' AS DATETIME), CAST('20120510' AS DATETIME) UNION ALL

    SELECT 'D2', CAST('20120502' AS DATETIME), CAST('20120607' AS DATETIME)

    SELECT * FROM #Files ORDER BY 2, 3

    DROP TABLE #Files

    So, from the data above, I need to calculate the following:

    DateActive jobs

    201201312

    201202292

    201203315

    201204304

    201205313

    201206302

    A job can be counted multiple times depending on when it was received and finished. Any advice would be appreciated. Thanks.

  • May 19, 2013 at 11:54 pm

    #1616514

    I think I may have found a solution. It's all in the joins. I created a recursive CTE to generate a framework of end-of-month dates covering the period of time required for the report. I then linked the job data back to the list of dates like this:

    SELECT CTEdates.EndofMonth, COUNT(Job)

    FROM CTEDates

    LEFT OUTER JOIN #Files ON #Files.Received <= CTEDates.EndofMonth

    AND ( #Files.Finished IS NULL OR #Files.Finished > CTEDates.EndofMonth )

    GROUP BY CTEdates.EndofMonth

    Does that make sense or is there a more efficient way of writing the query?

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