Power BI Distinct Descriptions: Combine Related Values with DAX

One of the most common Power BI challenges is displaying Power BI distinct descriptions from related tables especially when each row in your report needs a clean, de-duplicated summary of associated details. In this post, you’ll learn how to solve that exact problem using DAX functions like CONCATENATEX, DISTINCT, and SUMMARIZE.

The Scenario: Order Headers and Task Details

Let’s set the stage. Imagine you have:

• An Order Header table with one row per order.
• An Order Details table with multiple task items per order.

Each row in the Order Details table contains:

• A task ID
• A task description

The goal? To display a distinct, concatenated list of task descriptions in each row of the Order Header table.

Step 1: Understand the Data Model

The Order Header and Order Details tables are connected via the Order Number. This is a one-to-many relationship, where one order has many task details.

You’ll create a calculated column in the Order Header table to return the task descriptions for each order.

Step 2: Use RELATEDTABLE to Bring in Related Rows

To get all related rows from the Order Details table, use:

RELATEDTABLE('Order Details')

This function returns all rows related to each order from the Order Header table. You can use this as the base for iteration.

Step 3: Combine Descriptions with CONCATENATEX

Now iterate over the related rows and concatenate the task descriptions:

Task Description =
CONCATENATEX(
    RELATEDTABLE('Order Details'),
    'Order Details'[Task Description],
    " | "
)

This creates a pipe-delimited string of all task descriptions for each order. But there’s one problem: duplicates.

Step 4: Remove Duplicates with SELECTCOLUMNS + DISTINCT

To return only unique task descriptions, wrap your table expression in SELECTCOLUMNS and DISTINCT:

Task Description Distinct =
CONCATENATEX(
    DISTINCT(
        SELECTCOLUMNS(
            RELATEDTABLE('Order Details'),
            "Description", 'Order Details'[Task Description]
        )
    ),
    [Description],
    " | "
)

Explanation:

• SELECTCOLUMNS: Returns only the Task Description column.
• DISTINCT: Ensures repeated descriptions are removed.
• CONCATENATEX: Combines the unique values into a single text string.

This version meets the user’s goal: a clean, readable list of unique task descriptions per order.

Bonus: Using SUMMARIZE as an Alternative

Prefer SQL-style thinking? You can also use the SUMMARIZE function to achieve the same result:

Task Description Grouped =
CONCATENATEX(
    SUMMARIZE(
        'Order Details',
        'Order Details'[Task Description]
    ),
    'Order Details'[Task Description],
    " | "
)

SUMMARIZE implicitly returns a distinct list of the specified column, removing duplicates without needing DISTINCT.

When to Use Each Method

• SELECTCOLUMNS + DISTINCT: Great for flexibility and renaming columns.
• SUMMARIZE: Ideal if you’re used to SQL-style GROUP BY logic.
• RELATEDTABLE + CONCATENATEX: Best for simple use cases without duplicate values.

Each approach works choose the one that best suits your model and personal style.

Real-World Tip

This technique is powerful when building customer-facing reports where clarity and precision matter. By showing a clean list of distinct tasks, you improve user experience and avoid confusion.

Want to level up your DAX skills even more? Check out Data Bear’s Power BI Training for hands-on, real-world lessons in DAX, modeling, and report design.

Conclusion

Whether you’re creating operational dashboards or executive summaries, presenting Power BI distinct descriptions ensures your visuals are clean, accurate, and user-friendly especially when working with complex one-to-many data relationships