Presentación realizada en el Capítulo de Usuarios de SQL Server en Puerto Rico (PRPASS) en el mes de Octubre del 2012.
Presented during the monthly sessions of Puerto Rico PASS Chapter (www.prpass.org) - October, 2012.
Introduction to Data Analysis Expressions (DAX) Alan Koo President & Founder | Puerto Rico PASS Senior Consultant | Nagnoi, Inc.
Analysis Services 2012 Flavors • Personal BI: PowerPivot for Excel 2010 • Team BI: PowerPivot for Sharepoint • Corporate BI (SSDT): – Analysis Services 2012 Tabular – Analysis Services 2012 MultidimensionalTasting the Flavors of SSAS 2012 | SQL Saturday Puerto Rico | Alan Koo | www.alankoo.com
What is DAX• Programming language of SSAS 2012 Tabular and PowerPivot• Simple, clean, powerful, fast, not easy• Tabular requires simpler data modeling for good result• Thinking in DAX is a new attitude
BI Semantic Model: The Analysis Services 2012 Foundation From Personal to Corporate BI DAX MDXTasting the Flavors of SSAS 2012 | SQL Saturday Puerto Rico | Alan Koo | www.alankoo.com
Calculated Columns and Measures• Calculated Columns – Columns in the database, calculated with DAX – Stored in the database• Measures – DAX formulas computed on aggregates of values – Computed at query time• Different usages for different modeling needs
Calculated Columns• Formula is evaluated for each row• Results are stored back into PowerPivot as any other column• Columns can be used for both slicing data and summarizing values• Part of the model, available for use in any PivotTable• Usable by other AS clients in PowerPivot for SharePoint
DAX includes 80 Functions from ExcelDate and Time Information Math and Trig Statistical Text DATE ISBLANK ABS AVERAGE CONCATENATE DATEVALUE ISERROR CEILING, ISO.CEILING AVERAGEA EXACT DAY ISLOGICAL EXP COUNT FIND EDATE ISNONTEXT FACT COUNTA FIXED EOMONTH ISNUMBER FLOOR COUNTBLANK LEFT HOUR ISTEXT INT MAX LEN MINUTE LN MAXA LOWER MONTH Logical LOG MIN MID NOW AND LOG10 MINA REPLACE SECOND IF MOD REPT TIME IFERROR MROUND RIGHT TIMEVALUE NOT PI SEARCH TODAY OR POWER SUBSTITUTE WEEKDAY FALSE QUOTIENT TRIM WEEKNUM TRUE RAND UPPER YEAR RANDBETWEEN VALUEYEARFRAC ROUND ROUNDDOWN ROUNDUP SIGN SQRT SUM SUMSQ TRUNC 12
Calculated Measures• Evaluated dynamically per value in PivotTable• Part of the model, available to other PivotTables• Usable by any AS client through PowerPivot for SharePoint 13
DAX Aggregation Functions• SUM, AVERAGE, MIN, MAX, COUNT take column references• Extensions aggregate an expression over the rows of a table • SUMX (Table, Expression) • AVERAGEX (Table, Expression) • COUNTAX (Table, Expression) • MINX (Table, Expression) • MAXX (Table, Expression) • COUNTROWS (Table) 14
Useful Resources• Data Analysis Expressions (DAX) Overview – MSDN http://msdn.microsoft.com/en-us/library/gg399181.aspx• DAX in Action! – Alberto Ferrari in Project Botticelli ProjectBotticelli.com• SQLBI.com Articles http://www.sqlbi.com/articles/all/• Microsoft Business Intelligence y más… - Alan Koo alankoo.com
Calculated Columns• Calculated columns – Stored in the database, computed at process time – On big fact tables can consume a lot of RAM – Required to slice data• Measures – Computed at query time, do not use RAM• Prefer measures, whenever possible
Summary• DAX is fast: its speed of DAX makes simpler modeling techniques shine• Tabular requires thinking in DAX, less modeling, more complex expressions• PowerPivot is a great prototyping tool, models created in Excel can be deployed on SSAS Tabular
Credits for this Session• Ashvini Sharma – Microsoft Corporation• Alberto Ferrari and Marco Russo - SQLBI
Authorized Training Center Designed for professionals who want to use PowerPivot’s full capabilities, the PowerPivot Workshop is a two/three-day course that covers PowerPivot topics, starting from basic concepts and moving on up to complex data models and DAX formulas with the goal to facilitate the use of PowerPivot in the real world. Nestor Figueroa | 787.671.8244 firstname.lastname@example.org
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