Data analysis expressions
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Data Analysis Expressions, or DAX, is the native formula and query language for Microsoft PowerPivot and SQL Server Analysis Services Tabular models. DAX includes some of the functions that are used in Excel formulas, and additional functions that are designed to work with relational data and perform dynamic aggregation. It is, in part, an evolution of the Multidimensional Expression (MDX) language developed by Microsoft for Analysis Services multidimensional models (often called cubes) combined with Excel formula functions. It is designed to be simple and easy to learn, yet to expose the power and flexibility of PowerPivot and SSAS tabular models.
The Data Analysis eXpressions (DAX) language provides a specialized syntax for querying Analysis Services tabular model. DAX is NOT a programming language. DAX is a formula language. You can use DAX to define custom calculations for Calculated Columns and for Calculated Fields (measures) in Analysis Services Tabular Model.
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.
DAX Data Types
DAX can compute values for seven data types:
- Date (datetime)
- TRUE/FALSE (Boolean)
- BLOB (binary large object)
DAX has a powerful type-handling system so that you do not have to worry much about data types. When you write a DAX expression, the resulting type is based on the type of the terms used in the expression and on the operator used. Type conversion happens automatically during the expression evaluation.
- "Data Analysis Expressions (DAX) Overview". MSDN Library. Microsoft. Retrieved 28 November 2012.
- Collie, Rob (2012). DAX Formulas for PowerPivot: The Excel Pro's Guide to Mastering DAX. Tickling Keys. ISBN 9781615473328.
- Russo, Marco; Ferrari, Alberto; Webb, Chris (2012). Microsoft SQL Server 2012 Analysis Services: The BISM Tabular Model. Microsoft. ISBN 9780735658189.
- Tennick, Art (2012). Practical PowerPivot & DAX Formulas for Excel 2010. McGraw Hill Professional. ISBN 9780071746854.
- learn-with-video-tutorials. "Analysis Services Tabular Model - video tutorials". www.learn-with-video-tutorials.com.