MDAC 2.5 SDK - OLE DB Programmer's Reference
Chapter 21: OLE DB for OLAP Concepts
After establishing a connection and getting an interface on the session object, the consumer has to specify a query. Execution of a query results in a dataset. All data in a multidimensional data store exists as value points in one or more n-dimensional cubes. The result of a user query encompasses one or more cubes and extracts a set of points from these cubes as another p-dimensional cube. The value of p is usually no more than 4 and is typically 2 or 3. The resulting p-dimensional cube is called a dataset. This is similar to a query in a relational database system where the query encompasses one or more tables and returns a result set that has the same structure as that of a table.
Multidimensional OLE DB for OLAP provides a syntax called multidimensional expressions (MDX) to specify a dataset. MDX is a set of macros defined on top of SQL. Although these macros are generally useful for querying a multidimensional data source, their precise semantics are defined by means of their structured query language mappings.
Multidimensional expressions are discussed in greater detail in Chapter 24, "Multidimensional Expressions." Relevant topics include the following: