Cross join a dimension and measure

Question

I am new to MDX, looking at this query, why item(0) in the cross join in the [Top Product Sales] returns just Internet Sales Amount? Isn't the cross join supposed to return a set of (Product, Internet Sales Amount)?
WITH
MEMBER [Measures].[Top Product Sales] AS
EXISTING
TopCount(
[Product].[Product].[Product].Members,
1,
([Measures].[Internet Sales Amount])
{[Measures].[Internet Sales Amount]}
}.Item(0)
,FORMAT_STRING="Currency"
SELECT
([Measures].[Internet Sales Amount]),
([Measures].[Top Product Sales])
} ON COLUMNS,
([Date].[Calendar Year].[CY 2005]),
([Date].[Calendar Year].[CY 2006]),
([Date].[Calendar Year].[CY 2007]),
([Date].[Calendar Year].[CY 2008])
} ON ROWS
FROM [Adventure Works]
If I run the following query, I get a set from both dimensions (product and Internet Sales Amount), which makes sense to me, but why the above cross join return only Internet Sales Amount?
WITH
set x AS
TopCount(
[Product].[Product].[Product].Members,
1,
([Measures].[Internet Sales Amount])
{[Measures].[Internet Sales Amount]}
SELECT
{} ON COLUMNS,
x ON ROWS
FROM [Adventure Works]

Answer 1

Hi Thotwielder,
As you said that, the crossjoin return a set of (Product, Internet Sales Amount) which you can see on the screenshot below.
However, you use this set as a calculated measure, product is a dimension other than measure, so it will only use the Internet Sales Amount.
In your scenario, it seems that you want to get the top sales products for each year, right? If in this case, please try the query below.
SELECT
GENERATE
[Date].[Calendar].[Calendar Year].MEMBERS
,TOPCOUNT({[Date].[Calendar].CURRENTMEMBER*[Product].[Product].[Product]},1,[Measures].[Sales Amount]))
ON 1
,[Measures].[Sales Amount] ON 0
FROM [Adventure Works]
Results
If I have anything misunderstanding, please feel free to let me know.
Regards,
Charlie Liao
TechNet Community Support