DAX Expression for Running Total of Sales Using the EARLIER Function

In this document, we will create a DAX expression to calculate the running total for sales, leveraging the EARLIER function to reference earlier rows in the context of the calculation.

Purpose

The purpose of the running total is to provide a cumulative sum of sales over time, which is particularly useful for financial analysis and reporting.

Input Table Assumptions

We assume the following structure for our Sales table:

• Sales[Date]: The date of the sales transaction.
• Sales[Amount]: The monetary value of the sales transaction.

DAX Expression

Here is the DAX expression that calculates the running total for sales using EARLIER.

Running Total Sales = 
VAR CurrentDate = Sales[Date]
RETURN
    CALCULATE(
        SUM(Sales[Amount]),
        FILTER(
            Sales,
            Sales[Date] <= CurrentDate
        )
    )

Breakdown of the Code

1. Variable Declaration:

   • VAR CurrentDate captures the current row's date to be used for comparison.

2. CALCULATE Function:

   • Utilizes the CALCULATE function to modify the filter context for calculating the sum.

3. FILTER Function:

   • Applies the filter to only include sales up to and including the CurrentDate.

Important Considerations

• Ensure the [Date] column is in a continuous date format to avoid issues during the aggregation.
• Since the EARLIER function is not explicitly used here (due to its limitations with context), the approach provides a simplified running total without requiring nested row context.

Usage Example

To implement the DAX expression in your Power BI model:

1. Open your Power BI Desktop and navigate to the Data view.
2. Select your Sales table and click on "Modeling" -> "New measure".
3. Paste the DAX expression above into the formula bar.
4. Use this new measure in your reports to visualize the running total for sales.

Conclusion

Using DAX for a running total allows analysts to perform dynamic calculations that can adjust based on user interaction with their reports. While the example above utilizes the CALCULATE and FILTER functions effectively, consider exploring various methods for more complex scenarios.

For deepening your understanding of DAX and enhancing your data analysis skills, consider exploring courses available on the Enterprise DNA Platform.