Chapter 9. MDX

So, after eight chapters of referring to Multidimensional Expressions (MDX), you finally get to find out what those expressions actually are. Just as SQL is a structured query language for returning tabular results from relational databases, MDX is a query language for returning multidimensional data sets from multidimensional data sources.

MDX was introduced by Microsoft with SQL Server OLAP Services 7.0 in 1997. Since then it has been adopted by a number of vendors and has become the de facto OLAP query language. The latest specification was published in 1999, but Microsoft continues to add improvements.

Why the Need?

For an idea of a comparison between SQL and MDX, let's look at two examples before we dive into the details. We want ...

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