Write DAX Queries using DAX Studio

Write DAX Queries using DAX Studio
Alex Barbeau
[email protected]
Let’s get started
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Write DAX Queries using DAX Studio
Agenda
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Why Query with DAX?
DAX Studio
Demos!
Questions?
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DAX is a Query Language??
 Indeed it is!
 Measures are just one (very important) piece
 It’s tables all the way down
 Vectors and Matrices are a good theoretical start
 A query returns a table
 Queries are natively ‘Grouped By’
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Why Query Power BI/Tabular
 You need a data source for:
 Datazen
 SSRS
 SQL Server Reporting Services
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External Reporting Tool
Your own self-service BI from existing models
Need to extract data from Power BI Desktop
DAX Development
 Great way expand understanding of DAX
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Write DAX Queries using DAX Studio
Note on Terminology
 By Tabular I am referring to the framework
behind the following software:
 SSAS Tabular 2012-2016
 Power Pivot in Excel 2010-2016
 Power BI Desktop
 Query structure is the same in all
 Queries will use standard ‘Table’[Column]
references and [Measure] references
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Write DAX Queries using DAX Studio
Please ask Questions
 Odds are others have similar questions
 A full response may be delayed till a later
slide
 Some queries may be deliberately poorly
written to demonstrate concepts and syntax
 Basic familiarity with DAX assumed here-on
 Columnar storage
 CALCULATE(), VALUES(), FILTER()
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DAX Development
 Write queries and develop measures against
a new or existing model
 Power Pivot
 Visual Studio
 SSMS
 SQL Server Management Studio
 Excel (2013+)
 Edit DAX from a table
 Bit of an involved process
 DAX Studio
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Write DAX Queries using DAX Studio
DAX Studio
 It Queries!
 It Formats!
 It Traces!
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Write DAX Queries using DAX Studio
DAX Studio
 Open Source tool for querying Tabular
models
 http://daxstudio.codeplex.com/
 Developed (principally) by
 Darren Gosbell
 Marco Russo
 Query Excel, Tabular, and Power BI Desktop
 Let the team know what you think!
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Today’s Model
 Adventure Works Internet Sales
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EVALUATE
 Think of this like SELECT
 Does nothing without an expression to
 Wait for it
 EVALUATE
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ROW()
 Return a row of values
 ROW( <name>, <expression> [, <name2>,
<expression2>,…])
 <name> is any “text within quotes”
 <expression> is any DAX expression that returns
a scalar
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Write DAX Queries using DAX Studio
SUMMARIZE()
 Build tables as you need them
 SUMMARIZE(<table>, <groupBy_columnName>[,
<groupBy_columnName>]…[, <name>,
<expression>]…)
 <table>
 Any DAX expression that returns a table
 A table reference counts
 <groupBy_columnName>
 Any column in any table
 A column in a related table is a good start
 <name>, <expression>
 Just like ROW(), but now for the context defined above
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Write DAX Queries using DAX Studio
ADDCOLUMNS()
 Add values to a given table
 ADDCOLUMNS(<table>, <name>,
<expression>[, <name>, <expression>]…)
 <table>
 Any DAX expression that returns a table
 <name>
 Same as in ROW()
 <expression>
 Any DAX expression that returns a scalar for a given row in the <table>
 SUMMARIZE() returns a table…
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Write DAX Queries using DAX Studio
Best Practice Sidebar
 Best Practice to wrap ADDCOLUMNS()
around SUMMARIZE()
 Reduces unnecessary calculations
 Finer control over what is returned
 Generally faster
 Model dependent of course
 Exception is ROLLUP() commands, out of
scope for this session
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Write DAX Queries using DAX Studio
CALCULATETABLE()
 Efficient (generally) way to filter a query
 CALCULATETABLE(<expression>,<filter1>,<
filter2>,…)
 <expression>
 A DAX expression that returns a table
 <filter>
 Boolean expression or a table expression that
defines a filter
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DEFINE MEASURE
 Re-usable measures just for your query
 DEFINE MEASURE <tableName>[<name>] =
<expression>
 <tableName>
 An existing table in the data model
 <name>
 Same as prior slides
 <expression>
 A DAX expression that returns a scalar
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Write DAX Queries using DAX Studio
SUMX()
 Turning your query into a measure
 SUMX(<table>, <expression>)
 <tableName>
 An existing table in the data model
 <name>
 Same as prior slides
 <expression>
 A DAX expression that returns a scalar
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Write DAX Queries using DAX Studio
Resources
 DAX Studio
 http://daxstudio.codeplex.com/
 SQLBI.com
 Marco and Alberto wrote the book(s) on DAX
 DAX function Reference
 https://msdn.microsoft.com/en-us/ee634396
 Community
 MSDN Forums
 https://social.msdn.microsoft.com/Forums/sqlserver/enUS/home?forum=sqlkjpowerpivotforexcel
 Model
 https://awinternetsalestabularmodel.codeplex.com/
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Questions?
 Comments?
 Points of Rebuttal?
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SQL Saturday Evaluations
 Remember to fill out your online evaluations
for the event and any sessions you have
attended. They will be online until 10/17/15.
http://www.sqlsaturday.com/453/eventeval.aspx
http://www.sqlsaturday.com/453/sessions/sessione
valuation.aspx
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Write DAX Queries using DAX Studio

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