Set Functions: The StripCalculatedMembers() Function

April 7, 2008

This article is a member 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 real-world needs.

For more information about the series in general, as well as the software and systems requirements for getting the most out of the lessons included, please see my first article, MDX at First Glance: Introduction to MDX Essentials.

Note: Current updates are assumed for MSSQL Server, MSSQL Server Analysis Services, and the related Books Online and Samples.

Overview

In this lesson, we will introduce StripCalculatedMembers(), a basic set function which is often “just what the doctor ordered” in the context of the specific need. The general purpose of StripCalculatedMembers() is to retrieve the members of a specified set, after removing any calculated members.

StripCalculatedMembers() can be leveraged in a wide range of activities, from the support of simple list generation, to the support of sophisticated conditional and other calculations and presentations. We will introduce the function, commenting upon its operation and touching upon creative effects that we can employ it to deliver. As a part of our discussion, we will:

• Examine the syntax surrounding the function;
• Undertake illustrative examples of the uses of the function in practice exercises;
• Briefly discuss the results datasets we obtain in the practice examples.

The StripCalculatedMembers() Function

Introduction

According to the Analysis Services Books Online, the StripCalculatedMembers() function “returns a set generated by removing calculated members from a specified set.” StripCalculatedMembers() has numerous applications. For example, the function can be leveraged within queries to create datasets, in reporting applications such as MSSQL Server Reporting Services, for the support of picklists within the reports, for the support of axes within various end presentations, and so forth. The StripCalculatedMembers() function provides an intuitive option anytime we need to present, in a returned dataset, all members –minus calculated members – that belong to a specified set.

As we have noted to have been the case with many individual MDX functions we have examined within this series, combining StripCalculatedMembers() with other functions allows us to further extend its power. We will get a taste of this synergy in the practice exercises that follow.

We will examine the syntax for the StripCalculatedMembers() function after a brief discussion in the next section. We will then explore, from the straightforward context of MDX queries, and within practice examples constructed to support hypothetical business needs, some of the capabilities it offers the knowledgeable user. This will allow us to activate what we explore in the Discussion and Syntax sections, and afford us some hands-on exposure in creating expressions that employ the StripCalculatedMembers() function.

Discussion

To restate our initial explanation of its operation, the StripCalculatedMembers() function examines a set expression that we specify and returns the members that remain after it removes all calculated members. StripCalculatedMembers() can be used for a great deal more than simple list retrieval, as we have intimated. When coupled with other functions or used within MDX scripts, among other applications, we can leverage StripCalculatedMembers() to support a wide range of analysis and reporting utility.

Let’s discuss syntax to further clarify the operation of StripCalculatedMembers().

Syntax

Syntactically, in using the StripCalculatedMembers() function to return a set of members (minus calculated members), the set expression upon which we seek to apply the function is specified within the parentheses to the right of the StripCalculatedMembers keyword. The function removes calculated members from the set expression (a valid MDX expression that returns a set) enclosed within the parentheses, and returns a set representing only the base members contained within the scope of the set expression. As we shall see, StripCalculatedMembers() removes all calculated members from a set, including those added within the query itself (via the WITH MEMBER keywords). StripCalculatedMembers() also removes all calculated members added to a specified set using either of the AddCalculatedMembers() or .AllMembers functions, both of which return calculated members defined on the Analysis Server.

NOTE: For more detail surrounding the AddCalculatedMembers() function, see Set Functions: The AddCalculatedMembers() Function, and for information about the .AllMembers function, see Set Functions: The .AllMembers Function. Both articles are members of my MDX Essentials series at Database Journal.

For a general introduction to calculated members, together with a discussion of further considerations and perspectives involved in working with calculated members, see Calculated Members: Introduction and Calculated Members: Further Considerations and Perspectives, respectively, both of which are members of my MDX in Analysis Services series at Database Journal.

The general syntax for the application of StripCalculatedMembers() appears in the following string:

`  StripCalculatedMembers( <<Set_Expression>> )`

Putting StripCalculatedMembers() to work is straightforward. When using the function to return the members, minus any calculated members, contained within a set expression, we simply supply the required set expression within the parentheses to the right of the StripCalculatedMembers keyword.

As an example, say we specify, within a query executed against the sample Adventure Works cube, a column axis containing all members of the Product Categories level of the Product dimension (specified as {[Product].[Product Categories].[Category].MEMBERS}), with a row axis such as the following:

`  STRIPCALCULATEDMEMBERS( {[Measures].ALLMEMBERS} )`

Moreover, say that we add a WHERE clause to filter the retrieved data set to Calendar Year 2004. Depending upon the calculated members we have defined within our cube (we might have added calculated members beyond those that appear in the pristine sample cube), we would expect to retrieve results similar to those depicted in Illustration 1.

Illustration 1: Example Returned Data: StripCalculatedMembers() Function Employed in Query

We can see, within the dataset returned above, that only base members / measures appear. (If we remove the StripCalculatedMembers() from around the rest of the row axis specification, we will see that a greater number of measures (both base and calculated) now appear, and that the column axis increases dramatically (from 30 measures, in my local cube, to 50-plus measures).

Because of the relative ease with which we can employ StripCalculatedMembers(), and because of the flexibility with which we can exploit it to meet various business needs (particularly those meeting metadata requirements), the function can become a popular member of our analysis and reporting toolsets. It is easy, for example, when considering the above scenario, to see that we might simply parameterize “on / off” behavior for the StripCalculatedMembers() function within a client application, such as Reporting Services, to allow information consumers to choose either “include” or “exclude” behavior with regard to calculated members within axes or picklists at report run time.

We will get some hands-on exposure to the StripCalculatedMembers() function in the section that follows.