Introduction to MDX - Professional SQL Server Analysis Services 2005 with MDX - page 90

What Is MDX?
Just as SQL (Structured Query Language) is a query language used to
retrieve data from relational databases, MDX (Multi-Dimensional eXpres-
sions) is a query language used to retrieve data from multi-dimensional
databases. More specifically, MDX is used for querying data from OLAP
databases with Analysis Services and supports two distinct modes. When
used as an expression, it can define and manipulate multidimensional
objects and data to calculate values. As a query language, it is used to
retrieve data from Analysis Services databases. MDX was originally de-
signed by Microsoft and introduced along with Analysis Services 7.0 in
1998.
MDX is not a proprietary language; it is a standards-based query language used to
retrieve data from OLAP databases. MDX is part of the OLEDB for OLAP specific-
ation sponsored by Microsoft. Many other OLAP providers support MDX, including
Microstrategy's Intelligence Server, Hyperion's Essbase Server, and SAS's Enter-
prise BI Server. There are those who wish to extend the standard for additional func-
tionality, and MDX extensions have indeed been developed by individual vendors.
MDX extensions provide functionality not resident in the standard, but the constitu-
ent parts of any extension are expected to be consistent with the MDX standard.
Analysis Services 2005 does provide several extensions to the standard MDX
defined by the OLEDB for OLAP specification. In this topic you learn about the form
of MDX supported by Analysis Services 2005.
When one refers to MDX they might be referring either to the MDX query
language or to MDX expressions. Even though the MDX query language
has similar syntax as that of SQL, it is significantly different. Nonethe-
less, we will use SQL to teach you some MDX — we're not proud. Before
you get into the details of MDX query language and MDX expressions,
you need to learn some fundamental concepts.