Question

I have two tables, one with all my Branches, and one with all my sales. The sales table also contains a Sales Rep ID, a Branch ID, a month and a year.

I need a query that will return the sum of a specific rep’s sales for a year, grouped by branch and month, and the query must return 0 if there has been no sales in a branch for that month. I have the following, which does not return 0 if there are no sales:

SELECT
    s.Month,
    b.BranchName,
    SUM(s.InvoiceAmount) AS 'Sales'
FROM 
    Branch b
INNER JOIN
    Sales s ON s.BranchID = b.BranchID
WHERE
    s.Year = 2008
AND
    s.SalesRepID= 11
GROUP BY 
    s.Month,
    b.BranchName
ORDER BY 
    s.Month,
    b.BranchName

Answer 1

You will need to add the “missing” data to be able to join it.

SELECT
    b.BranchName,
    SUM(ISNULL(s.InvoiceAmount, 0)) AS 'Sales',
    s.Month
FROM 
    Branch b
    LEFT OUTER JOIN (
            SELECT
        b.BranchID AS BranchID
        , s.SalesRepID AS SalesRepID
        , Months.Month AS Month
        , Years.Year AS Year
        , 0 AS InvoiceAmount
      FROM 
          Sales s
          CROSS JOIN (
            SELECT 1 AS Month
            UNION ALL SELECT 2
            UNION ALL SELECT 3
            UNION ALL SELECT 4
            UNION ALL SELECT 5
            UNION ALL SELECT 6
            UNION ALL SELECT 7
            UNION ALL SELECT 8
            UNION ALL SELECT 9
            UNION ALL SELECT 10
            UNION ALL SELECT 11
            UNION ALL SELECT 12
            ) Months
          CROSS JOIN (
            SELECT 2007 AS Year
            UNION ALL SELECT 2008
            UNION ALL SELECT 2009
            ) Years
          CROSS JOIN Branch b
      UNION ALL SELECT 
        s.BranchID AS BranchID
        , s.SalesRepID AS SalesRepID
        , s.Month AS Month
        , s.Year AS Year
        , s.InvoiceAmount AS InvoiceAmount
      FROM Sales s      
    )s ON s.BranchID = b.BranchID    
WHERE
    s.Year = 2008
    AND s.SalesRepID= 11
GROUP BY 
    s.Month,
    b.BranchName
ORDER BY 
    b.BranchName,
    s.Month