⚡ DAX Query Basics – Data Types, Syntax & Functions

Last Updated: 15th October 2025

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DAX (Data Analysis Expressions) is a formula language used in:

• Power BI
• Power Pivot (Excel)
• SSAS Tabular Models

It helps you create custom calculations — like totals, averages, growth rates, comparisons, etc.

🗣 Hinglish Tip: DAX ko samjho Excel formulas ka “Power BI version” — par zyada smart aur dynamic!

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✏ DAX Syntax

DAX formula = Function Name + Arguments

NewColumn = FunctionName(TableName[ColumnName])

Example 👇

Total Sales = SUM(Sales[Amount])

💡 Syntax Breakdown:

SUM → Function name

( ) → Parentheses to enclose arguments

Sales[Amount] → TableName[ColumnName]

🧠 You can also create:

Calculated Columns → work row-by-row

Measures → work on aggregated data (dynamic)

-- Example of a Measure
Total Sales = SUM(Sales[Amount])

-- Example of a Calculated Column
Profit = Sales[Amount] - Sales[Cost]

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🧩 DAX Data Types

DAX supports these core data types:

Data Type	Description	Example
Whole Number	Integer values	100, -45
Decimal Number	Fractional values	123.45, -10.5
Currency	Fixed 4-decimal numeric (money)	₹1000.2560
Date/Time	Stores both date and time	2025-10-16 09:30
TRUE/FALSE	Boolean values	TRUE, FALSE
Text	String values	"Power BI", "India"
Blank	Represents empty or missing value	BLANK()

🗣 Tip: DAX automatically converts data types when needed (called implicit conversion).

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🔣 Writing DAX — General Syntax Rules

• Function names are not case-sensitive
• Always use square brackets [ ] for columns
• Use double quotes " " for text values
• Use comma (,) to separate function arguments
• Comments:

-- Single-line comment

/* Multi-line
   comment */

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🧮 Categories of DAX Functions

DAX has 250+ functions, but here are the main categories you’ll use daily:

Category	Purpose	Example Function
Text	Manipulate string values	LEFT(), CONCATENATE(), LEN()
Date & Time	Work with date or time	TODAY(), YEAR(), DATEDIFF()
Aggregate	Summarize or total values	SUM(), AVERAGE(), COUNT()
Logical	Make decisions	IF(), AND(), OR(), SWITCH()
Time Intelligence	Compare periods (YTD, QTD, etc.)	TOTALYTD(), SAMEPERIODLASTYEAR()
Filter	Modify data context	CALCULATE(), FILTER(), ALL()
Table	Return or combine tables	SUMMARIZE(), UNION(), VALUES()
Statistical	Perform ranking or distribution	RANKX(), PERCENTILEX.INC()

We will cover these in more detail in the coming sections.

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