You know that sinking feeling when your Power BI report finally loads… after what feels like an eternity?
I’ve been working with Power BI for years now, and I keep seeing the same DAX mistakes crop up again and again. Not just from beginners, mind you – I see experienced developers making these errors too. And honestly? I’ve made most of them myself at some point.
The frustrating bit is that these mistakes are absolutely sneaky. Your report runs. It gives you numbers. Everything looks fine. But then you realise it’s running slower than a Sunday morning, or worse – the numbers are completely wrong.
So I put together a video walking through the five most common DAX mistakes I’ve encountered, and more importantly, how to sort them out properly.
Why This Matters
Here’s the thing – when you’re making these mistakes, you don’t always know it straight away. You might spend hours trying to work out why your report takes forever to load, or why your totals don’t quite add up. I’ve been there, staring at formulas at 11pm wondering what on earth I’ve done wrong.
The good news? Once you know what to look for, these issues are actually quite easy to fix. And the difference it makes is massive. We’re talking about reports that load in seconds instead of minutes, formulas that are half the length, and results you can actually trust.
What You’ll Learn
In the video, I cover five specific mistakes:
Using calculated columns when you should be using measures. This one alone can cut your file size in half. I’ve seen it happen loads of times.
Ignoring context transition. Sounds technical, I know, but it’s actually the key to understanding why your formulas aren’t working the way you expect.
Not using variables. This makes your code cleaner, easier to read, and often faster too. Once you start using them, you’ll wonder how you ever managed without.
Confusing row context and filter context. This trips people up constantly. Get this straight, and suddenly a lot of DAX starts making sense.
Writing complicated time calculations manually. There are built-in functions that do this in three lines instead of twenty. Why make life harder than it needs to be?
Each one includes real examples using the AdventureWorks database, so you can follow along and see exactly what I’m on about.
Who This Is For
Whether you’re just getting started with DAX or you’ve been using Power BI for a while, chances are you’ll recognise at least one of these mistakes. I certainly did when I was putting the video together – there were a few “oh, that’s why that happened” moments.
The best part is, you can apply these fixes immediately. Watch the video, adjust your formulas, and you’ll see the difference right away.
Ready to Sort Out Your DAX?
I’ve put the full tutorial up on YouTube, complete with step-by-step examples and side-by-side comparisons of the wrong and right approaches.
Watch the video here:
And if you find it helpful, I’d really appreciate it if you could give it a like and subscribe. I’m putting together more DAX tutorials like this, covering everything from the basics through to the really advanced stuff.
Got questions? Drop them in the comments on the video, I read every single one and I’m happy to help.
Want to go deeper?
If you’re serious about mastering DAX, I’ve written a comprehensive book that covers everything from the fundamentals through to advanced techniques, complete with real business scenarios and practical examples.
Check it out on Amazon: Mastering DAX in Power BI