DAX Handlers Function for Buyer Customer Insights

DAX Function: Handlers

This section contains a DAX function designed to calculate the number of buyers' customers based on specific date ranges within a dataset.

Purpose

The function Handlers calculates a value based on the maximum date selection and defines a rolled-up date range of three months back, alongside the end of the previous month, while accounting for all selected records.

Function Definition

Handlers = 
VAR _MIN = EDATE(MAX(dly_trans_snp[Start Of Month]), -3)             -- First day, 3 months ago
VAR _MAX = MAX(dly_trans_snp[Start Of Month]) - 1                    -- Last day from last month (closed month)
VAR _MIN_ALL = CALCULATE(MIN(dly_trans_snp[Start Of Month]), ALLSELECTED(dly_trans_snp)) -- Min date for base
RETURN
    IF(
        SELECTEDVALUE(dly_trans_snp[Start Of Month]) = _MIN_ALL, 
        [# Buyers Customers],
        CALCULATE(
            [# Buyers Customers],
            FILTER(
                ALLSELECTED(dly_trans_snp),
                dly_trans_snp[date] >= _MIN &&
                dly_trans_snp[date] <= _MAX 
            )
        )
    )

Explanation of Each Component

1. Variables:

   • _MIN: This variable calculates the date that is three months before the maximum date in the Start Of Month column.
   • _MAX: This variable determines the last date of the previously closed month.
   • _MIN_ALL: This variable calculates the minimum date across all selected records.

2. IF Statement:

   • The IF function checks if the currently selected date is equal to the globally minimum date. If true, it returns the measure [ # Buyers Customers] directly.
   • If false, it uses CALCULATE to filter the dataset, bounded by the current _MIN and _MAX, focusing on the number of buyers' customers within that range.

Input Validation

• Ensure the data in dly_trans_snp[Start Of Month] and dly_trans_snp[date] is in date format to avoid errors.
• Validate that [ # Buyers Customers] is a defined measure before executing this function.

Real-World Usage Example

Consider a scenario where you want to analyze customer buying trends over the last three months, excluding the current month. Implement the Handlers function within a Power BI report page:

1. Add this measure to your report.
2. Create a visual to display customer counts.
3. Use slicers to filter your dataset further while observing how the count adjusts in real-time based on user selections.

Conclusion

This DAX function illustrates efficient handling of date ranges and dynamic calculations within a dataset, adhering to best practices in DAX coding, promoting code reusability and performance optimization.

For further enhancement of your DAX skills, consider exploring courses on the Enterprise DNA Platform that delve into advanced DAX techniques and real-world applications.