DAX Formula for Previous Month Total Amount

Objective

To calculate the total amount for the previous month utilizing the DATEADD function in DAX.

DAX Formula

The following DAX formula can be used to achieve the previous month's total amount:

PreviousMonthTotal = 
CALCULATE(
    SUM(Sales[Amount]),
    DATEADD(Date[Date], -1, MONTH)
)

Explanation of the Formula

1. CALCULATE Function: This function changes the context in which data is evaluated. It allows you to perform operations based on modified filter conditions.

2. SUM(Sales[Amount]): This part of the formula sums up the Amount column in the Sales table. Sales[Amount] is the field from which summed values are generated.

3. DATEADD(Date[Date], -1, MONTH):

   • Date[Date]: Refers to the date column in your Date dimension table.
   • -1: Indicates that we are looking back one month.
   • MONTH: The unit of time being altered, which in this case is a month.

The combination of these components results in a calculation that effectively aggregates sales amounts from the prior month based on the current filter context.

Practical Example

Assuming you have a data model with the following two tables:

• Sales Table:

  • Columns: OrderID, Amount, OrderDate

• Date Table:

  • Columns: Date, Month, Year

Scenario

• You want to display the previous month's total sales in a report or dashboard for analysis purposes.

Steps

1. Ensure that your Sales table is linked to the Date table through the OrderDate.
2. Create a new measure in Power BI with the DAX formula provided above.
3. Use this measure in your reports, pivot tables, or visualizations to see the total sales for the previous month.

Conclusion

This DAX formula serves as a robust method for calculating previous month totals by leveraging time intelligence functionalities provided by DAX. This can enhance your analytical capabilities when dealing with time-based data trends. For further learning and mastery, consider exploring courses available on the Enterprise DNA Platform.