DAX was developed by the SQL Server Analysis Services team at Microsoft as part of Project Gemini and released in 2009 with the first version of the PowerPivot for Excel 2010 Add-in. Both DAX and MDX can be used to query PowerPivot and Tabular models, however only MDX may be used to query multidimensional SSAS models (cubes) in versions of SSAS up to SQL Server 2012 RTM. Future versions of SSAS (both multidimensional & tabular models) will support DAX natively.
