Wednesday 27 December 2023

What context style is allowed by Power BI DAX? Power BI interview questions and answers 168

 What context style is allowed by Power BI DAX?

Power BI DAX supports two primary context styles:

1. Row Context:

  • Focuses on calculations within individual rows of a table.

  • Automatically generated for each row during evaluation.

  • Accesses values from the current row using column names directly.

  • Commonly used for calculations that involve comparisons or aggregations within a table.


Code snippet

Total Sales = SUM(Sales[Amount])  // Calculates total sales within the current row's context

2. Filter Context:

  • Determines which rows of a table are considered for calculations.

  • Can be influenced by filters applied in visuals, slicers, or through DAX functions like CALCULATE.

  • Allows you to create dynamic calculations that respond to user interactions.


Code snippet

Total Sales in Selected Region = CALCULATE(SUM(Sales[Amount]), FILTER(Sales, Sales[Region] = "East"))
// Calculates total sales for the East region, adjusting to any filters applied in visuals or slicers

Additional Context Styles:

  • Query Context: The overall context of the entire query being evaluated.

  • Evaluation Context: The complete set of filters and context from all surrounding expressions.

Key Points:

  • DAX calculations are context-aware, meaning results depend on the current context.

  • Understanding context styles is crucial for creating accurate and dynamic DAX measures.

  • You can manipulate context using DAX functions like CALCULATE, FILTER, ALL, ALLSELECTED, and more.

Best Practices:

  • Be mindful of context when writing DAX measures.

  • Test measures thoroughly with different filters and scenarios to ensure correct results.

  • Utilize visual tools like the DAX Studio to trace evaluation steps and understand context flow.

I'm here to help if you have any further questions about context styles or DAX in Power BI!

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