Siksha Sarovar

Siksha Sarovar (sikshasarovar.com) is a free educational web application that helps students in India learn programming and prepare for academic and competitive exams. The platform offers structured coding courses (C, C++, Python, Java, HTML, CSS, PHP, Power BI, AI, Machine Learning, Data Science), complete university curriculum notes for BCA/MCA students with previous year question papers, Class 10 and Class 12 CBSE/HBSE school notes, and dedicated preparation material for SSC, UPSC, Banking, Railway and other government exams. Browsing the site is completely free and requires no account. Users may optionally sign in with Google solely to save their learning progress, quiz scores and personal preferences across devices.

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Siksha Sarovar is a free e-learning platform for coding courses, BCA university notes and competitive exam preparation. Optional Google sign-in saves your learning progress across devices.

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3.1 What is DAX? Why is it Important?

Lesson 22 of 62 in the free Power BI notes on Siksha Sarovar, written by Rohit Jangra.

What is DAX?

DAX stands for Data Analysis Expressions. It is a formula language used in Power BI, Excel Power Pivot, and SQL Server Analysis Services (SSAS) for creating custom calculations and analyses.

Why is DAX Important?

Core of Power BI calculations — all measures, calculated columns, and calculated tables use DAX • Dynamic analysis — DAX formulas respond to user interactions (filters, slicers, drill-downs) • Business logic — implement complex business rules that go beyond simple aggregations • Time intelligence — built-in functions for year-over-year, running totals, and period comparisons • Essential skill — required for anyone building professional Power BI reports

DAX vs Excel Formulas

FeatureExcel FormulasDAX
ScopeWorks on cellsWorks on columns and tables
ContextCell reference (A1, B2)Row context and filter context
Data SizeLimited (1M rows)Millions of rows efficiently
PurposeCell-level calculationsAggregate and analytical calculations
Syntax=SUM(A1:A10)SUM(Sales[Amount])
Dynamic FilteringManualAutomatic (responds to filters)

DAX Syntax Basics

Referencing Columns: TableName[ColumnName] Example: Sales[Amount], Products[Category]

Referencing Measures: [MeasureName] Example: [Total Sales], [Profit Margin]

Creating a Measure:

Total Sales = SUM(Sales[Amount])

Creating a Calculated Column:

Profit = Sales[Revenue] - Sales[Cost]

Types of DAX Calculations

TypeDescriptionExample
MeasuresDynamic aggregations that respond to filtersTotal Sales = SUM(Sales[Amount])
Calculated ColumnsNew columns computed row by rowProfit = [Revenue] - [Cost]
Calculated TablesEntire tables created from DAX expressionsDateTable = CALENDAR(DATE(2020,1,1), DATE(2025,12,31))

Where to Write DAX

Formula Bar — at the top of the Report/Data view • New Measure button — Home or Modeling tab • New Column button — in Data view • New Table button — Modeling tab