Season 2

Namaste Power BI

Episode 16

DAX Aggregations

⏱ 35:00

Episode Summary

Beyond SUM — SUMX, AVERAGEX, COUNTAX, MINX, MAXX and the difference between simple aggregators and iterator functions. Understanding how iterators walk row-by-row through a table.

This is Episode 16 of the free Namaste Power BI course on DevWithData — covering dax aggregations. Watch the video above, then pass the MCQ checkpoint to unlock the next episode and update your Data Readiness Index score.

Key Takeaways

→SUM/AVERAGE/COUNT are simple aggregators over a single column
→SUMX/AVERAGEX are iterators — they evaluate an expression per row
→Iterators create a row context on each row of the table
→SUMX is needed when your calculation involves multiple columns per row

⚠ Common Interview Pitfalls

•Using SUM(A*B) — this doesn't work; you need SUMX(table, A*B)
•Forgetting that iterators create row context (affects context transition)
•Using iterators when a simple aggregator would suffice (performance cost)

Official Reference

Deepen your understanding with official Microsoft documentation.

PL-300 Official Training Course

Microsoft's official instructor-led training for the Power BI Data Analyst certification.

https://learn.microsoft.com/en-us/training/courses/pl-300t00

Power BI Documentation

Complete reference for Power BI Desktop, Power BI Service, and Power BI Embedded.

https://learn.microsoft.com/en-us/power-bi/

Content on DevWithData is original and inspired by official Microsoft resources. The links above point directly to Microsoft Learn — always the authoritative source.

← Ep 15: Season 1 Wrap-up & Review

Ep 17: CALCULATE Deep Dive →

Episode Checkpoint

Sign in to attempt the quiz and unlock the next episode.