Congratulations, you have made it through the first three chapters! Ostensibly you should now feel free to take on the rest of the chapters in no particular order, but you got this far, so why not go immediately to Chapter 4 and jump right in? Now you know the fundamental elements of MDX — cells, members, tuples, and sets. Further, you learned that MDX has two forms: queries and expressions.
You saw that MDX queries, which are used to retrieve data from Analysis Services databases, retain a superficial resemblance to SQL, but that the resemblance breaks down the more you drill down on the details. MDX expressions, on the other hand, are simple yet powerful constructs that are partial statements — by themselves they do not return results like queries. The expressions are what enable you to define and manipulate multidimensional objects and data through calculations, like specifying a default member's contents, for example.
To solidify your basic understanding of MDX, you learned the common query statements, WITH, SELECT, FROM, and WHERE, as well as the MDX operators like addition, subtraction, multiplication, division, and rollup, and the logical operators AND and OR. These details are crucial to effective use of the language. You got a good look at the eleven MDX function categories; saw the four forms MDX functions can take, and even saw some detailed examples of some commonly used functions like Filter, ParallelPeriod, MemberToStr, and StrToMember. You learn more advanced MDX concepts and functions in Chapters 7, 8, and 9. All the MDX functions supported in Analysis Services 2005 are provided in Appendix A with examples. Coming up next in Chapter 4 are the details of creating a data source, a data source view, and how to deal with multiple data source views in a single project.