| Multidimensional Expressions |
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HISTORY MDX was first introduced as part of OLEDB for OLAP specification in 1997 from Microsoft . The specification was quickly followed by commercial release of Microsoft OLAP Services 7.0 in 1998, and later by Microsoft Analysis Services . While it was not an open standard, but rather a Microsoft owned specification, it was adopted by the wide range of OLAP vendors, both servers - Applix , Microstrategy , SAS , SAP , Whitelight , NCR and clients - Panorama, Proclarity, Cognos, Business Objects, Brio, Crystal etc. mdXML In 2001 the XMLA Council, released the XML For Analysis standard, which included mdXML as a query language. In the current XMLA 1.1 specification, mdXML is essentially MDX wrapped in XML MDX DATA TYPES There are six primary data types in MDX Scalar Scalar is either a number or a string. It can be specified as a literal, i.e. number 5 or string "OLAP" or it can be returned by MDX function, i.e. ''Aggregate'' (number), ''UniqueName'' (string), ''.Value'' (number or string) etc. Hierarchy Hierarchy is a dimension hierarchy of a cube. It can be specified by its unique name, i.e. '' {Link without Title} . {Link without Title} '' or it can be returned by MDX function, i.e. ''.Hierarchy''. Level Level is a level in dimension hierarchy. It can be specified by its unique name, i.e. '' {Link without Title} . {Link without Title} . {Link without Title} '' or it can be returned by MDX function, i.e. ''.Level''. Member Member is a member in dimension hierarchy. It can be specified by its unique name, i.e. '' by qualified name, i.e. ''[Time .[Fiscal].[2006].[Q2].[August]'' or returned by MDX function, i.e. ''.PrevMember'', ''.Parent'', ''.FirstChild'' etc. Tuple Tuple is an ordered collection of one or more members from different hierarchies. Tuples can be specified enumerating the members, i.e. ''( [Customer . Geography . Customers . [Measures .[Sales])''or returned by MDX function, i.e. ''.Item''. Set Set is an ordered collection of tuples with the same hierarchality (dimensionality). It can be specified enumerating the tuples, i.e. ''{( [Time .[Fiscal].[2006]), ( [Time .[Fiscal].[2007])}'' or returned by MDX function or operator, i.e. ''Crossjoin'', ''Filter'', ''Order'', ''Descendants'' etc. Other data types In limited contexts, MDX allows other data types as well - for example Array can be used inside ''SetToArray'' function, Dimension can be used inside ''Leaves'' function etc. Objects of other data types are represented as scalar strings indicating the object names, such as measure group name in ''MeasureGroupMeasures'' function or KPI name in ''KPIValue'', ''KPIGoal'' etc functions. BOOKS
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