Intrinsic Member Properties: The MEMBER_VALUE Property
September 12, 2008
About the Series ...
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.
In this lesson, we will examine another intrinsic member property, MEMBER_VALUE. As many of us are aware, and as we have confirmed in various other articles within this series, the intrinsic member properties supported by SQL Server 2005 Analysis Services are of two types: context sensitive member properties and non-context sensitive member properties. MEMBER_VALUE belongs to the second group of properties. As a general group, intrinsic member properties provide additional information that can be used by applications to enhance the ultimate user experience. Support for the non-context sensitive member properties is the same for all members, regardless of individual context.
The purpose of the MEMBER_VALUE property is to support the return of a value for the member with which it is associated. MEMBER_VALUE can be useful in a host of different applications. Moreover, as I have noted to be the case for other functions and properties within the MDX Essentials series, MEMBER_VALUE allows us to exercise a great deal of presentation sleight of hand, in working with MDX in Analysis Services, as well as within Reporting Services and various other reporting applications that can access an Analysis Services cube.
The MEMBER_VALUE property can be leveraged in activities that range from generating simple lists to supporting sophisticated presentations. It is a particularly effective tool when we need to provide parameter picklist support and the like, as we shall see. We shall introduce the function, commenting upon its operation and touching upon examples of effects that we can employ it to deliver. As a part of our discussion, we shall:
The MEMBER_VALUE Property
According to the Analysis Services Books Online, the MEMBER_VALUE property specifies the value of the member in the original type. The MEMBER_VALUE property is set within the ValueColumn element of the Source properties group for a given dimension attribute, as we shall see.
NOTE: For more information on the Source group of attribute properties, together with the MEMBER_VALUE property, see my Database Journal article Dimension Attributes: Introduction and Overview, Part V, a member of my Introduction to MSSQL Server Analysis Services series.
As we shall see in the initial Preparation steps of our Practice session below, the ValueColumn property allows us to specify the column within the underlying data source from which Analysis Services derives the value of the attribute. Within this setting, we may find either the None or the New option (a third option, representing a preselected column, will exist if a column has already been selected not the case in our current example, but possibly different elsewhere).
As we noted in Dimension Attributes: Introduction and Overview, Part V, if we have specified a value in the NameColumn property, then the same value is used as the default in ValueColumn. If we did not specify a value in the NameColumn property, and the KeyColumns collection of the attribute contains a single KeyColumn element representing a key column with a string data type, the same values are used as default values for the ValueColumn element.
MEMBER_VALUE has many applications, including the rather obvious uses with Analysis Services members that are included in the definition, as well as its pairing with other MDX functions to leverage its power even further. For example, as we have seen is the case with the .Name function (among many other functions), in earlier articles of this series, MEMBER_VALUE can also be synergistically combined with the .CurrentMember function; we will see an example of this specific combination within the practice exercises below.
We will examine the syntax involved in leveraging the MEMBER_VALUE property after our customary overview in the Discussion section that follows. After that, we will conduct practice examples within a couple of scenarios, constructed to support hypothetical business needs that illustrate uses for the property. This will afford us an opportunity to explore some of the presentation options that MEMBER_VALUE can offer the knowledgeable user. Hands-on practice with MEMBER_VALUE, where we will create expressions that leverage the function, will help us to activate what we learn in the Discussion and Syntax sections that follow.
To restate our initial explanation of its operation, the MEMBER_VALUE property, when acting upon a member, returns the assigned value of the object to which it is appended with the period (.) delimiter. MEMBER_VALUE can be used for a great deal more than the support of simple lists of unique object names, as we have intimated. When we couple it with other functions, we can leverage MEMBER_VALUE to deliver a wide range of analysis and reporting utility. As in so many cases with the Microsoft integrated business intelligence solution, consisting of MSSQL Server, Analysis Services and Reporting Services, this function, residing within the Analysis Services layer, can be extended to support capabilities and attributes in the Reporting Services layer. Knowing where to put the intelligence among the various layers is critical to optimization, in many cases. For more of my observations on this subject, see Multi-Layered Business Intelligence Solutions ... Require Multi-Layered Architects.
The MEMBER_VALUE property returns, as we have noted, the value contained within the column of the underlying data source from which Analysis Services derives the value of the attribute, and can be used for querying and display, among other, purposes. Lets look at some syntax illustrations to further clarify the operation of MEMBER_VALUE.
Syntactically, anytime we employ the MEMBER_VALUE property to return the associated value, the member for which we seek to return the value is specified to the left of MEMBER_VALUE. The property takes the object to which it is appended as its argument, and returns, within its original data type, the value of the object specified. The general syntax is shown in the following string:
In short, putting MEMBER_VALUE to work couldnt be easier. When specifying the property to return the value of a member or members, we simply append it to the right of the member(s) under consideration.
As is typically the case with MDX functions, operators and properties, the MEMBER_VALUE property can often be best leveraged by combining it with other functions, operators or properties, particularly relative functions, to generate lists of names, and so forth, as we shall see in short order.
NOTE: For information on several of the relative functions, see my article MDX Member Functions: "Relative" Member Functions, within the Database Journal MDX Essentials series.
We will practice some uses of the MEMBER_VALUE property in the section that follows.