Named sets are simply MDX expressions defined with an alias that return a set of members. If you find yourself writing complex MDX expressions to return a set of members often or if you have a commonly used expression, consider creating a named set. This will prevent you from having to duplicate your work.
To create a named set, open your SSAS project and head to the Calculations tabs. Find the icon with the curly brackets and click it.
Give your named set a name. For this example, I’m using the Adventure Works 2008 R2 cube and I’m creating a named set to return the top ten products with the highest Internet Sales Amount.
The MDX to return the top ten products with the highest Internet Sales Amount is very simple. We will use the TopCount function, which accepts three arguments.
The first argument is the dimension attribute we wish to return. The second argument is how many members will be returned in the set, and the last argument is the measure we would like to use to rank the members returned.
If I wanted to create a named set to return the Bottom 10 Products with the lowest Internet Sales Amount, I could write the same expression seen below except in place of the TopCount function I would use the BottomCount function.
When we create our named set, we can specify it as a Dynamic Named Set or a Static Named Set. A Dynamic Named Set respects the context of the subcube and the where clause and is evaluated at the time the query is executed. A Static Named Set is evaluated at the time the cube is processed and will not respect any subcube context and slicers in your where clause.
Here is the calculation script for the named set:
CREATE DYNAMIC SET CURRENTCUBE.[Top 10 Products]
[Measures].[Internet Sales Amount]
The next time we process our cube, our named set will be available for use in our calculations and reports.
To use our named set in an MDX query, all I have to do is use the Named Set’s alias, [Top 10 Products].
Named Sets are powerful and very useful, but they can sometimes take a long time to write, especially if the expression is complex or if you are new to MDX. That’s where BI xpress steps in. BI xPress is a powerful tool used to speed up and augment SSAS and SSIS development. BI xPress also recently won the Gold Editors Choice Award from SQL Server Magazine.
To open the BI xPress Calculation Builder, open your SSAS project in BIDS, navigate to the Calculations tab and click the BI xPress Calculation Builder icon.
This will open the MDX Calculation Builder Wizard. Select the calculation or named set you would like to build. Scroll to the bottom to find the Sets templates. I’m selecting the Top 10 Count template.
The first step is to select the attribute that you would like returned by the set. As before, I’m selecting the Product attribute of the Product dimension.
Then select the measure that you want to use to rank the selected attribute. I’m selecting the Internet Sales Amount measure.
After I click next and give my calculation a name, the named set has been added to my calculation script in my cube.
To download the free trial of BI xPress, head over to PragmaticWorks.com and check out BI xPress. You won’t regret it after you see how much time it will save you with your SSAS and SSIS development.