MDAC 2.5 SDK - OLE DB Programmer's Reference
Chapter 24: Multidimensional Expressions
OLE DB for OLAP defines multidimensional expressions (MDX), which provide a rich syntax for specifying a dataset. MDX can be viewed as a set of macros defined on top of the SQL language. Although these macros are generally useful for querying a multidimensional data source, their precise semantics are defined by means of their SQL language mappings.
For more information about SQL language mappings, see Chapter 26, "Mapping MDX to SQL Statements."
The following sections discuss concepts of MDX and provide examples of its use.