Set Functions: The DrillUpLevel() Function
April 3, 2006
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 member lessons, please see Set Functions: The DRILLDOWNMEMBER() Function, where important information is detailed regarding the applications, samples and other components required to complete our practice exercises.
In this article, we will continue the examination of "MDX for drilling up and down" that we began in Set Functions: The DrillDownMember() Function. We have discussed the nature of drilling, in general, in previous articles of our sub-series, stating that it comprises an analytical technique through which means an information consumer can maneuver between summarized ("drilling up") and detailed ("drilling down") levels of data. We noted that drilling up or down occurs along the lines of drilling paths that are defined within the structure of our cubes, and which are typically specified by the cube's dimensional hierarchies. We mentioned, too, that these paths can be based upon alternative relationships that exist within or between dimensions.
An example might be described as follows, based upon an engagement within which I have recently been involved: An executive within a state Department of Education wishes to examine annual Adequate Yearly Progress (AYP) data within a cube constructed primarily to allow comparison and analysis of those results at various levels. The executive can examine national averages, numbers of test takers, and various other measures, and then perform a drilldown operation within a Geography dimension that might then present the data by states. He could then perform subsequent drilldowns to display state regions (or perhaps even congressional districts), counties / school systems, and more. Depending upon the design of the cube, the drilldown process could ultimately take the consumer to the level of the individual schools perhaps even to the individual students themselves.
Drilling up is a capability that might be taken for granted in a drilldown scenario such as the foregoing. From any of the drilled down levels at which the information consumer finds himself or herself, a corresponding capability to navigate upward, from more detailed levels of data to more summarized levels of data, would be an expected complementary feature.
In an earlier article, Set Functions: The DrillDownLevel() Function, we introduced the "primary," level-directed MDX drilldown function, DrillDownLevel(), stating that it supports the capability of Analysis Services to meet the common need for drilldown from a point within a given Set to members within the next lower level, or to a level which we can specify using an optional Level Expression (or, alternatively, an optional Index). Drilling up from a level-directed perspective is supported by a function, DrillUpLevel(), that is quite similar to DrillDownLevel(), with respect to its operation, differing, of course, in the "direction" (upward versus downward, along the drilling path) of its action.
In this article we will examine a means for drilling in the "upward" direction, through the DrillUpLevel() function, another "staple" support function underpinning drill capabilities within MDX. DrillUpLevel() drills up the members of a set to a higher level. It drills up each member of a specified set that exists below a level that we can optionally specify. (If we do not specify the level, the function identifies the lowest level in the set, and removes the members that reside at that level, to present a drilled up state at the next level).
In a manner similar to other functions that we have examined in the MDX Essentials series, DrillUpLevel() can be useful in a host of different reporting and analysis applications. DrillUpLevel(), along with other "navigational" functions like it (virtually all of which we examine in other articles of this series) 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. Like other MDX functions in general, the DrillUpLevel() function can be leveraged, within and among the various "layers" of the Microsoft integrated Business Intelligence solution, to support sophisticated presentations and features. We will 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 will: