Introduction
DAX (Data Analysis Expressions) is the formula language for Power BI, enabling calculated columns, measures, and complex analytics.
Basic Measures
Total Sales = SUM(Sales[Amount])
Average Order = AVERAGE(Sales[Amount])
Sales YTD = TOTALYTD(SUM(Sales[Amount]), 'Date'[Date])
CALCULATE Function
Sales Last Year =
CALCULATE(
[Total Sales],
SAMEPERIODLASTYEAR('Date'[Date])
)
Time Intelligence
MoM Growth =
DIVIDE(
[Total Sales] - [Sales Last Month],
[Sales Last Month]
)
Best Practices
- Use measures over calculated columns for aggregations
- Create a dedicated Date table
- Use variables for readability
- Test with DAX Studio for performance
Conclusion
Mastering DAX unlocks advanced analytics in Power BI. Start with basic aggregations and progressively add time intelligence and CALCULATE patterns.
