About the Series ...
This is the twentieth article of the series, MDX
Essentials. The series is designed to provide hands-on application of the
fundamentals of the Multidimensional Expressions (MDX) language, with
each tutorial progressively adding features designed to meet specific
For more information about the series in general, as well as
the software and systems requirements needed for getting the most out of the
lessons included, please see the first article, MDX at First Glance: Introduction to MDX Essentials.
Note: Service Pack 3 updates are assumed for MSSQL
Server 2000, MSSQL Server 2000 Analysis Services, and the related Books
Online and Samples.
What We Accomplished in our Last Article
last article of the series, Subset
Functions: The Head() Function, we
introduced the Head() function, whose general purpose is to return a
specified number of elements from the beginning of a set, preserving natural
order. We commented upon the operation of the function, and then examined its
syntax. Next, we undertook practice examples with the function, based upon
hypothetical business requirements. Our practice included the creation of
queries to meet illustrative business needs, as well as demonstrations of the
manner in which the Head() function handles various numeric expression
input scenarios. Throughout the practice examples, we briefly discussed the
results datasets we obtained with regard to the Head() function,
together with other surrounding considerations.
this lesson, we continue a "triptych" of articles that expose set
functions that deal specifically with subsets - that is, each function returns
a subset of a larger set as part of its operation. Having covered the Head()
function in the previous article, we will introduce the Tail() function
in this article, then follow it with the Subset() function in the next
article. As we mentioned in our last session, these three functions have much
in common with regard to usage and operation; covering them in close proximity
will allow us to more finely distinguish among them, to exploit the attributes
we can leverage to meet specific business needs.
general purpose of the Tail() function is to return the last specified
number of elements in a set. We will introduce the Tail()
function, commenting upon its operation, and then we will:
Examine the syntax surrounding the function;
Undertake illustrative examples of the uses of the function in
Briefly discuss of the results datasets we obtain in the practice