DAX Function for Total Sales Calculation

DAX Function to Multiply Quantity and Price from Different Tables

Objective

Create a DAX function that multiplies Quantity from one table with Price from another table and returns the result.

Assumptions

• Sales table includes a column Quantity.
• Product table includes a column Price.
• Both tables have a relationship through a common column ProductID.

DAX Function

Total Sales Amount = 
    SUMX(
        Sales, 
        Sales[Quantity] * RELATED(Product[Price])
    )

Code Explanation

1. SUMX Function: It iterates over a table (Sales in this case), and for each row, performs the multiplication of the Quantity column from the Sales table and the Price column from the Product table.
2. RELATED Function: Used to fetch related data from the Product table through the established relationship using ProductID.
3. Multiplication: For each row in the Sales table, Sales[Quantity] is multiplied by RELATED(Product[Price]).
4. Sum: SUMX then aggregates these multiplied values.

Usage Example

To use the Total Sales Amount measure in a report:

1. Model Setup:

   • Ensure there is a relationship between Sales and Product tables via ProductID.

2. Data Model:

   Sales Table	Product Table
   ProductID	ProductID
   Quantity	Price

   • Example data:

     Sales	Product
     ProductID: 1	ProductID: 1
     Quantity: 10	Price: 100
     ProductID: 2	ProductID: 2
     Quantity: 20	Price: 150

3. Create Measure:

   • Add the provided DAX formula as a measure in your data model.

4. Visualization:

   • Use the Total Sales Amount measure in visualizations to show the total sales amount, reflecting correct calculations across tables.

Best Practices

• Validate Relationships: Ensure correct relationships are established in your data model, necessary for the RELATED function to work properly.
• Input Validation: Although DAX doesn't have explicit input validation, always ensure the data types and relationships are correctly set in your model.
• Documentation: Commenting and descriptive names improve readability and maintenance.

Further Learning

For more advanced techniques regarding DAX measures and relationships, consider courses on the Enterprise DNA platform.

By following these structured steps, the solution ensures efficiency, readability, and adherence to best practices in DAX and Power BI modeling.