MDX Essentials: Set and String Functions: The GENERATE() Function

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: Service Pack 3 updates are assumed for MSSQL Server 2000, MSSQL Server 2000 Analysis Services, and the related Books Online and Samples.

Overview

In this lesson, we will introduce a function that provides us the ability to derive a set by systematically applying a set expression to each of the members of a set we define. GENERATE() is a potent function in our MDX toolset, in that it enables us to select precisely only certain members of a dimension level. It effectively operates upon two sets to create a new set, based upon the members of a second set that are also in a primary set.

We will consider elementary uses of the GENERATE() function in this article, and then explore more sophisticated uses in subsequent articles. As with the Basic Functions articles within this series, our objective is to build a foundation in the rudiments of the function, from which we can expand to more sophisticated exploitation in subsequent articles.

As we have noted the case to be with many other MDX functions, the GENERATE() function can be leveraged to perform tasks that range from the simple to the sophisticated. For that matter, in the limited body of knowledge that is commonly available surrounding MDX in general, at this writing, hands-on references to GENERATE() remain elusive, with the few documents that discuss the function describing it as “complex.” We will introduce the function, commenting upon its operation and touching upon uses at a general level, and then we will:

• Examine the syntax surrounding the function;
• Undertake illustrative examples of the use of the function, in a couple of practice exercises;
• Briefly discuss the results datasets we obtain in the practice examples.
William Pearson
Bill has been working with computers since before becoming a "big eight" CPA, after which he carried his growing information systems knowledge into management accounting, internal auditing, and various capacities of controllership. Bill entered the world of databases and financial systems when he became a consultant for CODA-Financials, a U.K. - based software company that hired only CPA's as application consultants to implement and maintain its integrated financial database - one of the most conceptually powerful, even in his current assessment, to have emerged. At CODA Bill deployed financial databases and business intelligence systems for many global clients. Working with SQL Server, Oracle, Sybase and Informix, and focusing on MSSQL Server, Bill created Island Technologies Inc. in 1997, and has developed a large and diverse customer base over the years since. Bill's background as a CPA, Internal Auditor and Management Accountant enable him to provide value to clients as a liaison between Accounting / Finance and Information Services. Moreover, as a Certified Information Technology Professional (CITP) - a Certified Public Accountant recognized for his or her unique ability to provide business insight by leveraging knowledge of information relationships and supporting technologies - Bill offers his clients the CPA's perspective and ability to understand the complicated business implications and risks associated with technology. From this perspective, he helps them to effectively manage information while ensuring the data's reliability, security, accessibility and relevance. Bill has implemented enterprise business intelligence systems over the years for many Fortune 500 companies, focusing his practice (since the advent of MSSQL Server 2000) upon the integrated Microsoft business intelligence solution. He leverages his years of experience with other enterprise OLAP and reporting applications (Cognos, Business Objects, Crystal, and others) in regular conversions of these once-dominant applications to the Microsoft BI stack. Bill believes it is easier to teach technical skills to people with non-technical training than vice-versa, and he constantly seeks ways to graft new technology into the Accounting and Finance arenas. Bill was awarded Microsoft SQL Server MVP in 2009. Hobbies include advanced literature studies and occasional lectures, with recent concentration upon the works of William Faulkner, Henry James, Marcel Proust, James Joyce, Honoré de Balzac, and Charles Dickens. Other long-time interests have included the exploration of generative music sourced from database architecture.