Adding Calculations to the Cube - Expert Cube Development with SSAS Multidimensional Models - page 164

THIS = AGGREGATE (
(YTD ([Date Order].[Calendar].CurrentMember) *
[Date Order].[Date Calculations].[Real Value]),
Measures.CurrentMember
);
END SCOPE;
The CREATE MEMBER statement is straightforward: it creates the calculated member
and gives it a default value of Null . The SCOPE is the part that does the magic: from
everything from the Date level up to the Calendar Semester level, when the Year To
Date member is selected in the Date Calculations hierarchy, it aggregates the set
returned by YTD by the Real Value member and the current Measure.
We can see from the screenshot that the Year-To-Date calculation works with both
Sales Amount and Gross Profit, even though we did not write any specific code for
the two measures. Moreover, the screenshot shows why the Real Value member is
needed: it is the reference back to the original physical space of the cube, while Year
To Date is the new virtual plane in the multidimensional space that holds the results
of our calculation.