Tuesday, January 22, 2013

PowerPivot-DAX

Self service business analytics and in-memory analytics are a couple of streams that are going to see coverage this year based on various publications and technical magazines. I had written some basic blog posts about PowerPivot recently. One of the big weapons in the SSAS arsenal was the MDX language. Yes the MDX language has a quite a bit of a steep learning curve. The ones who acheived a certain level of mastery of MDX are/were able to extend the SSAS cubes built to provide various analytic information. In the same fashion in order to provide extended capabilities in PowerPivot, there is a new language available in the Powerpivot Domain Called DAX. The purpose of DAX is very similar to that of MDX in SSAS, the construct provides a lot of functions in order to calculate different type of aggregations,relations and averages. DAX provides the user with simple functions and that goes all the way to more complex functions.
When a user is in the PowerPivot window, for example where there are different worksheets with the Dimensions and the fact table, DAX functions can be used to get derived data. Let us say there is a worksheet called DimProduct which has all the columns in the DimProduct table. One can add a calculated column where in the user can type in a function called RELATED, this is a function available as part of the DAX construct. In this case one would type =RELATED(DimTable[ColumnName]), this function returns how the present Dimension table say DimProduct is related to the other dimension table listed in the RELATED function. As one can see here that it is possible to draw various relations between the tables, this could be very helpful in creating computed columns which can be later used in the PowerPivot Analysis that can be done using PIVOT tables.

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