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Nulls turning into zeros in Analysis Services 2000 Cube

Posted on 2006-11-10
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Last Modified: 2008-02-01
Hello Experts

I have a fact table in SQL2000. There are some columns in the fact table used as measures in an Analysis Services 2000.
In the SQL table, there are several rows that contain null values. In the cube, these appear as zeros.

Is there a way I can tell Analysis services to preserve the null values and not convert them to zeros?
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Question by:molar
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by:rw3admin
ID: 17916474
not to sure about Analysis, but is default for that column set to 0? if yes then it will insert a 0 for every NULL
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by:rw3admin
ID: 17916484
hold on, isnt the idea of a cube is to save the summary data? if your Summary is count then you are going to get a 0 and as I said I am not sure about analysis ... but maybe other summary operations will also do the same,
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by:molar
ID: 17916643
Hi rw3admin

There is no default on the SQL column. In the SQL table, the contents correctly reports as null for some rows.

Analysis Services can be used for Summaries but it also holds the detailed data on each member. These member variables contain 0 as a value instead of null.

Where I'm aggregating, the aggregations are a sum rather than a count. For the purposes of the report it doesn't matter a great deal how they aggregate it is the detailed member variables i am interested in.

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regbes earned 500 total points
ID: 17916914
Hi molar,

why dont you do a drill through then?

rw3admin is right AS saves the 0 so that the aggregations will work

if you do a drill through you can get to the data you want then your OLAP client will be able to drill through to the base data in your fact table


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by:molar
ID: 17917004
Hi regbes, are you saying that AS can't hold a null value?

The client tool I am using has more formatting options for OLAp data as opposed to SQL data, and I'm trying to reproduce the look of an existing report.  That's why I'd rather stick to doing it in a cube if I can.

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by:molar
ID: 17917039
Looking at Books Online, it looks as though null value are possible as there is a section on calculated members that reads...

"You can use the following techniques when you create calculated members:

Null keyword
You can use the keyword Null to create a calculated member whose value is null."



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by:regbes
regbes earned 500 total points
ID: 17917235
molar,

sorry im at home so cant test but i havent been able to get my base data to show the underlying nulls, you should be able to add a calculation(calculated measure) to the cube and using some sotr of iif have it return a null, the base data would of been aggragated hence getting rid of the nulls  
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by:molar
ID: 17919964
I  found this on null values in  "MDX Solutions Second Edition" by George Spofford and others, published by Wiley Press.

"In Analysis Services 2005, empty values in fact table measure columns can be captured as NULL cell values
when the measure’s NullProcessing property is set to “Preserve,” which is a change from Analysis Services 2000 in which empty values measure columns resulted in zero for cell values."

Thanks for your help guys. It looks like this is a limitation of SSAS2000 after all.

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by:regbes
ID: 17920700
molar,
> it is the detailed member variables i am interested in.

as soon as my users start drillong down and showing a lot of detail (over 3000 rows) in their OLAP client (mainly Excel for us) things start to get very slow.

if the report is static this may not be an issue for you but if your users slice and dice with large result sets watch out for performance hits
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