I'm trying to calculate the total sales of a product in a month, but I would like it to include any "empty" months (with no sales) and only select the latest 12 months.
This is my code so far.
declare
@ProductNo int
set @ProductNo = 1234
SELECT
YEAR(o.OrderDate) as 'Year', MONTH(o.OrderDate) as 'Month', sum(Amount) as 'Units sold',[ProductNo]
FROM [OrderLine] ol
inner join [Order] o on ol.OrderNo = o.OrderNo
where ProductNo = @ProductNo
Group by ProductNo, YEAR(o.OrderDate), Month(o.OrderDate)
Order by ProductNo, YEAR(o.OrderDate), Month(o.OrderDate)
This returns
Year Month Units sold
2011 6 2
2011 10 1
2011 11 1
2012 2 1
But I would like it to return.
Year Month Units sold
2011 4 0
2011 5 0
2011 6 2
2011 7 0
2011 8 0
2011 9 0
2011 10 1
2011 11 1
2011 12 0
2012 1 0
2012 2 2
2012 3 0
I'm using SQL Server 2008 R2 Sp1