Starting out with DAX

When starting to use DAX, the issues or challenges people face often revolve around their background. Heavy Excel users are often comfortable, for example, with some of the simple aggregations, but filters can be a challenge, while Database Developers can find the flexibility daunting. What you must understand is that Power BI’s DAX is an incredibly flexible language. This flexibility is also what makes it so difficult for many to understand.

Back in 2015, when first starting to use Power Pivot, Ross remembers struggling with CALCULATE ( ); in Power Pivot, you create measures in a canvas away from where you can use them. He remembers trying to apply all the context to the measures so that the value shown in the box was correct, then massively overcomplicating the measures while also slowing them down due to multiple FILTER ( ) clauses. It was a revelation to realise that SUM ( Table[Column Name] ), was all that was needed as the context would be provided by the pivot table that was being built.

Over the years of running Super User Communities and training colleagues in Power BI and DAX, we have seen patterns we use to point to when people are ready for the next stage.

Common Challenges We Look for

1. Grasping the Concept of Context

One of the first hurdles many learners face with DAX is understanding the concept of context. Context is a fundamental aspect of DAX that determines how calculations are performed. There are two types of context: row context and filter context. Row context refers to the current row being evaluated in a table, while filter context refers to the set of filters applied to the data model. Understanding how these contexts interact is crucial for writing accurate DAX formulas.

2. Transitioning from Excel to DAX

Many Power BI users come from an Excel background, where they are accustomed to using Excel formulas. Transitioning from Excel to DAX can be challenging because, despite their similarities, DAX operates within a different framework. Excel users need to adjust their mindset and learn to leverage the unique capabilities of DAX. Understanding the differences between Excel and DAX functions and becoming familiar with Power BI’s data modelling concepts are essential steps in this transition.

3. Mastering the Use of Functions

DAX contains lots of functions, and mastering their use takes years. It is not uncommon for people to “think” they understand a function, then overuse it or even misuse it. Ross, for example, misused FILTER ( ), thinking all filters needed to be applied that way, all while complaining about how “dumb” it was.

2. Practice, Practice, Practice

Practice is key to mastering any skill, and DAX is no exception. Working on real-world scenarios and datasets allows learners to apply their knowledge and gain practical experience. Creating sample projects, participating in Power BI challenges, and experimenting with different DAX functions can help reinforce learning and build confidence. Find a dataset that you know; if you are passionate about it, that’s even better. Look to explore that data and gradually expand what you are doing within it.

3. Start with Simple Formulas

Commencing with simple formulas and progressively advancing to more complex ones can facilitate a manageable learning process. Initially, focus on mastering basic functions and gradually integrate more sophisticated techniques. Decomposing complex problems into more minor, manageable components can establish a solid foundation and mitigate feeling overwhelmed. DAX permits iterative measures, making simple measures referenced within more intricate ones. Consequently, you can deconstruct complex measures and systematically test them as they are developed.

4. Understand the Data Model

A strong understanding of the data model is crucial for writing effective DAX formulas. Before diving into DAX, take the time to understand the relationships between tables and how data is structured. This knowledge will provide a solid foundation for creating calculations and measures that accurately reflect the data. The data model will shape how context is evaluated within your measures. This means you will have to write measures in a particular way depending on the situation.

An effective data model will greatly simplify the DAX you need to write, so be prepared to revisit your model if you find issues with its use.

5. Seek Feedback and Collaboration

Collaborating with peers and seeking feedback from more experienced users can accelerate the learning process. Sharing your work, discussing challenges, and learning from others’ experiences can provide new perspectives and solutions. Participating in Power BI user groups and online communities can facilitate collaboration and knowledge exchange. Look to join or establish a Super User Community within your organisation. The benefits provided to an organisation from having a super user community far exceed any costs incurred.

Let’s continue to support each other in this journey, sharing knowledge and inspiration as we master the art of Power BI DAX together. Geordie Consulting can be your invaluable partner in learning Power BI and DAX, offering extensive expertise and tailored support to meet your organisation’s unique needs. Their team of seasoned professionals can provide customised training sessions, ensuring a comprehensive understanding of both fundamental and advanced DAX functions. Moreover, Geordie Consulting’s collaborative approach encourages ongoing dialogue and feedback, helping to address specific challenges and refine your data models for optimal performance. By leveraging their industry knowledge and practical insights, your organisation can unlock the full potential of Power BI, driving impactful data visualisations and informed decision-making processes.