Practice
Preparation: Access SQL Server Management Studio
To reinforce our understanding of the basics we have
covered, we will use the IsGeneration() function within a couple of
queries that illustrate its operation, focusing, within this article, upon
scenarios where we use the function to support conditional logic within
a calculation. (We examine its use in combination with the MDX Filter()
function in another article of this series). We will undertake our practice
exercises within scenarios that place IsGeneration() within the context
of meeting basic requirements similar to those we might encounter in our
respective daily environments. The intent is to demonstrate the use of the function
in a straightforward, memorable manner.
We will turn to the SQL Server Management Studio as a
platform from which to construct and execute the MDX we examine, and to view
the results datasets we obtain. If you do not know how to access the SQL
Server Management Studio in preparation for using it to query an Analysis
Services cube (we will be using the sample Adventure Works cube in
the Adventure Works DW Analysis Services database), please
perform the steps of the following procedure, located in the References
section of my articles index:
Prepare
MSSQL Server Management Studio to Query Analysis Services
This procedure will take us through opening a new Query
pane, upon which we will create our first query within the section that
follows.
Procedure: Satisfy Business Requirements with MDX
Let’s assume, for purposes of our practice example, that we
have received a request for assistance from representatives of our client, the Adventure
Works organization. Analysts within the Controllers’ Group, with whom we
have worked in the past to deliver solutions to meet various reporting and
analysis needs, inform us that they have received a request to generate some
simple values for a specific analysis task that has been discussed at a recent
meeting with the Controllers.
The analysts tell us that the values under immediate
consideration involve Internet Order Counts, but, as is typically the
case in our collaborative sessions, they want to develop an approach that will
work equally well with other measures that have similar analysis potential. (As
we have noted in other sessions of our series, our client colleagues often
derive parameterized queries in Reporting Services from the basic MDX
syntax we assemble together, and can thus create self-serve reports that allow
information consumers to dictate what measure they wish to analyze, and myriad
other options, at run time.) The desired end is to simply return the Internet
Order Count recorded for each of the four operating calendar years
contained within the Adventure Works cube.
As is often the case, this basic need might be easily met a
number of ways with an MDX query. The analysts throw a further twist into the
requirement, however: In addition to being likely to parameterize the calendar
year, and perhaps other date specifics at runtime, they also want to be
able to support parameterization of the level within the Date
dimension (Calendar hierarchy) when executing the report (that is, to be
able to change it from calendar year to a lower level, such as a quarter
of a month, for example – and thus to “narrow” the member selection that
appears within a given iteration of the report results, producing something
akin to a selective “drilldown” effect.) Once
again, the richness of MDX affords us a number of avenues to this objective.
While parameterization is itself not a consideration in our current level of
query design, we want to make it easy to accomplish within Reporting
Services. (The same concepts would, of course, apply with other OLAP
reporting tools that afford developer access to the MDX syntax that underlies
them).
After we initially explain the use of the IsGeneration() function
as one candidate for meeting the requirement, our client colleagues state that
they are interested in understanding how they might apply conditional logic
via this function, within the context of a practical scenario such as the immediate
requirement. A method of testing whether or
not a specified member lies within a given generation number (or numbers)
of a specific dimensional hierarchy is something that they hope to be able to extrapolate
to uses within other dimensions, as well. (As we note often within the MDX Essentials series, time / date
dimensions are always good “starters” for introducing new functions. The relationships
between the various levels are familiar to everyone, whereas the structures of
other dimensions might not lend themselves to population accuracy and
completeness “reasonability” testing undertaken by those not entirely
knowledgeable of the corporate structure, geography, and so forth.)
We offer to illustrate the use of IsGeneration() to
meet the immediate need, proposing to present a couple of examples, to solidify
the analysts’ new understanding, as well as to assist in rounding their overall
MDX “vocabularies.” We then set about the assembly of our examples to
illustrate uses of IsGeneration().
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