Grouping MDX query results - ssas

Question

I have a following query (based on sample data provided with Microsoft® SQL Server® 2008 MDX Step by Step book):
WITH
SET important_months AS
{
([Product].[Product Categories].[Subcategory].&[28].CHILDREN , {[Date].[Month of Year].&[1], [Date].[Month of Year].&[2]}),
([Product].[Product Categories].[Product].&[477] , {[Date].[Month of Year].&[3]})
}
SELECT [Measures].[Order Count] ON COLUMNS,
important_months ON ROWS
FROM [Step-by-Step]
The query shows the number of orders placed on products in a particular subcategory in particular months. For all products in category 28, i need the count of orders placed in January or February (month 1 or 2). Exceptions are orders placed on product 447: in this
case, I additionally need to include number of orders placed in March.
In the end however, I'm not really interested in details regarding months:
all I want, is simple number of orders placed on a particular product (i.e. I want to loose/hide the information about what was the month the order was placed).
So instead of
Mountain Bottle Cage, January, 176
Mountain Bottle Cage, February, 183
Road Bottle Cage, January, 141
Road Bottle Cage, February, 152
Water Bottle - 30 oz, January, 381
Water Bottle - 30 oz, February, 403
Water Bottle - 30 oz, March, 414
I need to have:
Mountain Bottle Cage, 359 (176 + 183)
Road Bottle Cage, 293 (141 + 152)
Water Bottle - 30 oz., 1198 (381 + 403 + 414)
I tried with putting the important_months set into a where clause, but (besides circular reference error due to custom set) I wouldn't be able to project the
categories on rows axis (would I?). Also, I thought of using a subquery, but it appears I cannot refer to the important_months set there either.
In other words: I need to get result that in SQL i would get by issuing
SELECT SUM([Order Count])
FROM <MDX RESULT HERE>
GROUP BY Product
Can it be done?

Answer 1

An educated guess is that MDX Subqueries is the solution. Did you try using tuples in the subselect :
WITH
SELECT [Measures].[Order Count] ON COLUMNS,
{[Product].[Product Categories].[Subcategory].&[28].CHILDREN,[Product].[Product Categories].[Product].&[477]} ON ROWS
FROM (
SELECT
{([Product].[Product Categories].[Subcategory].&[28].CHILDREN,{[Date].[Month of Year].&[1], [Date].[Month of Year].&[2]}),
([Product].[Product Categories].[Product].&[477],{[Date].[Month of Year].&[3]})} ON 0
FROM [Step-by-Step]
)

Answer 2

You're creating an asymmetric set (with March for Water Bottle only), so you can't really slice this directly in the WHERE clause without including it for all other products.
icCube's answer looks good to me, with one small addition: add a DISTINCT to the row selection to combine Water Bottle back into one row.
WITH
SELECT [Measures].[Order Count] ON COLUMNS,
DISTINCT {[Product].[Product Categories].[Subcategory].&[28].CHILDREN, [Product].[Product Categories].[Product].&[477]} ON ROWS
FROM (
SELECT
{([Product].[Product Categories].[Subcategory].&[28].CHILDREN,{[Date].[Month of Year].&[1], [Date].[Month of Year].&[2]}),
([Product].[Product Categories].[Product].&[477],{[Date].[Month of Year].&[3]})} ON 0
FROM [Step-by-Step]
)