SQL Group and Sum By Month - Default to Zero

Question

I am currently grouping and summing inventory usage by month:

SELECT      Inventory.itemid AS ItemID,
            SUM(Inventory.Totalunits) AS Individual_Mon         


        

Answer 1

You could prepare a 'calendar' table like so:

DECLARE @d datetime
SET @d = @StartRange

DECLARE @calendar TABLE (Date datetime)

WHILE (@d <= @EndRange) BEGIN
    INSERT INTO @Calendar VALUES (@d)
    SET @d = DATEADD(month, 1, @d)
END

and then do a LEFT JOIN with your table on the month and year date parts. This way you'll always have all the months between the start and end date as rows.