DAX Function to Count Overdue Records

This guide will take you step by step through the creation of a DAX function that counts the number of overdue records. We'll ensure our code is well-documented, includes input validation, and adheres to robust coding practices.

Function Documentation

Purpose

The function CountOverdueRecords calculates the number of overdue records based on a due date field and the current date.

Parameters

• DueDate (Date): The column containing the due date for each record.

Return Type

• Returns an integer value representing the count of overdue records.

Assumptions

• The dataset has a column named DueDate which contains valid date values.

Exceptions

• Handles cases where the DueDate column is missing, empty, or contains invalid data gracefully.

DAX Function

/* 
    Function: CountOverdueRecords
    Purpose: Count the number of records that are overdue based on the due date.
    Parameters: 
      - DueDate (Date): Column containing the due date for each record.
    Returns: Integer - Total count of overdue records.
*/

CountOverdueRecords = 
VAR CurrentDate = TODAY() -- Get today's date

RETURN
CALCULATE(
    COUNTROWS('TableName'), -- Replace 'TableName' with the actual table name
    'TableName'[DueDate] < CurrentDate, -- Condition to check if the due date is in the past
    NOT(ISBLANK('TableName'[DueDate])), -- Ensure due date is not blank
    ISNUMBER('TableName'[DueDate]) -- Ensure due date is a valid date number
)

Step-by-Step Explanation

1. Define the Current Date: CurrentDate = TODAY()

   • This variable stores the current date.

2. Count Overdue Records:

   • COUNTROWS('TableName'): Replace 'TableName' with the actual name of your table.
   • 'TableName'[DueDate] < CurrentDate: Condition to check if the due date is earlier than the current date.
   • NOT(ISBLANK('TableName'[DueDate])): Ensures the due date is not blank.
   • ISNUMBER('TableName'[DueDate]): Ensures the due date is a valid date number.

Usage Example

Suppose you have a table named Tasks with a column DueDate. You want to count how many tasks are overdue. Here's how you can use the CountOverdueRecords function in a practical example:

Example Table

Tasks Table:

Implementing the Function

CountOverdueTasks = 
VAR CurrentDate = TODAY()

RETURN
CALCULATE(
    COUNTROWS('Tasks'),
    'Tasks'[DueDate] < CurrentDate,
    NOT(ISBLANK('Tasks'[DueDate])),
    ISNUMBER('Tasks'[DueDate])
)

Result Interpretation

Running the function CountOverdueTasks would return the number of tasks whose DueDate is before today's date, ensuring all due dates are valid and not blank.

Conclusion

This structured approach ensures your DAX function to count overdue records is not only functional but also adheres to best practices in software engineering. For further learning and to master more advanced DAX concepts, consider exploring courses on the Enterprise DNA Platform.