Variables (VAR/RETURN) in Power BI - Dashboard Guide

Dashboard Mode - Variables (VAR/RETURN)

Business Question

How can we use variables in DAX to calculate the average sales per order and highlight orders above this average?

Sample Data

OrderID	Customer	SalesAmount	OrderDate
1001	Alice	250	2024-01-10
1002	Bob	400	2024-01-15
1003	Charlie	150	2024-01-20
1004	Diana	500	2024-01-25
1005	Eva	300	2024-01-30

Dashboard Components

• KPI Card: Average Sales per Order
  Formula:
  

  Average Sales =
  VAR TotalSales = SUM(Sales[SalesAmount])
  VAR OrderCount = COUNTROWS(Sales)
  RETURN DIVIDE(TotalSales, OrderCount)

  
  Result: (250+400+150+500+300)/5 = 320
• Table: Orders with Highlight
  Columns: OrderID, Customer, SalesAmount, Above Average?
  Formula for "Above Average?":
  

  Above Average? =
  VAR AvgSales = CALCULATE(
      DIVIDE(SUM(Sales[SalesAmount]), COUNTROWS(Sales))
  )
  RETURN IF(Sales[SalesAmount] > AvgSales, "Yes", "No")

  
  Rows:
  1001 - 250 - No
  1002 - 400 - Yes
  1003 - 150 - No
  1004 - 500 - Yes
  1005 - 300 - No
• Bar Chart: Sales Amount by Customer
  X-axis: Customer
  Y-axis: SalesAmount
  Bars show sales per customer

Dashboard Layout

+----------------------+----------------------+
|  Average Sales KPI   |   Sales by Customer  |
|       (320)          |      (Bar Chart)     |
+----------------------+----------------------+
|               Orders with Highlight Table           |
|                (OrderID, Customer, SalesAmount, Above Average?)              |
+-----------------------------------------------------+

Interactivity

A slicer on OrderDate allows filtering orders by date range. When the date range changes, the Average Sales KPI, Orders with Highlight Table, and Sales by Customer Bar Chart update automatically to reflect only the selected orders.

Self Check

If you add a filter to show only orders with SalesAmount greater than 300, which components update and how?

• The Average Sales KPI recalculates the average using only orders with sales above 300 (orders 1002 and 1004), so average becomes (400+500)/2 = 450.
• The Orders with Highlight Table shows only orders 1002 and 1004, with 1002 marked "No" (400 < 450) and 1004 marked "Yes" (500 > 450) for "Above Average?".
• The Sales by Customer Bar Chart updates to show only customers Bob and Diana with their sales amounts.

Key Result

Dashboard showing average sales per order using variables, highlighting orders above average, with sales by customer chart.

Practice

1. What is the main purpose of using VAR in a DAX formula?

easy

A. To store a value temporarily for reuse within the formula

B. To create a new table in the data model

C. To filter rows in a table

D. To format the output of a measure

Solution

1. Step 1: Understand the role of VAR in DAX

   VAR is used to define a variable that holds a value temporarily inside a formula.

2. Step 2: Identify what VAR does in calculations

   It allows reuse of the stored value to simplify and speed up calculations.

3. Final Answer:

   To store a value temporarily for reuse within the formula -> Option A

4. Quick Check:

   VAR stores values temporarily [OK]

Hint: VAR holds values inside formulas for reuse [OK]

Common Mistakes:

• Thinking VAR creates tables
• Confusing VAR with filters
• Assuming VAR formats output

2. Which of the following is the correct syntax to define and return a variable in DAX?

easy

A. VAR Total = SUM(Sales[Amount]) RETURN Total

B. RETURN Total = SUM(Sales[Amount]) VAR Total

C. DEFINE VAR Total = SUM(Sales[Amount]) OUTPUT Total

D. LET Total = SUM(Sales[Amount]) THEN Total

Solution

1. Step 1: Recall correct DAX variable syntax

   In DAX, variables are defined with VAR and the result is returned with RETURN.

2. Step 2: Match syntax with options

   VAR Total = SUM(Sales[Amount]) RETURN Total uses VAR to define and RETURN to output, which is correct.

3. Final Answer:

   VAR Total = SUM(Sales[Amount]) RETURN Total -> Option A

4. Quick Check:

   VAR then RETURN is correct syntax [OK]

Hint: VAR first, then RETURN to output [OK]

Common Mistakes:

• Swapping VAR and RETURN order
• Using keywords like DEFINE or LET incorrectly
• Missing RETURN keyword

3. Consider the following DAX measure:

Measure = VAR SalesAmount = SUM(Sales[Amount]) VAR Tax = SalesAmount * 0.1 RETURN SalesAmount + Tax

What is the output of this measure if the total sales amount is 1000?

medium

A. 100

B. 1100

C. 900

D. 10

Solution

1. Step 1: Calculate SalesAmount variable

   SalesAmount = SUM(Sales[Amount]) = 1000.

2. Step 2: Calculate Tax variable

   Tax = SalesAmount * 0.1 = 1000 * 0.1 = 100.

3. Step 3: Calculate RETURN value

   Return SalesAmount + Tax = 1000 + 100 = 1100.

4. Final Answer:

   1100 -> Option B

5. Quick Check:

   1000 + 10% tax = 1100 [OK]

Hint: Calculate variables stepwise, then add in RETURN [OK]

Common Mistakes:

• Using only SalesAmount without tax
• Multiplying instead of adding tax
• Confusing tax rate calculation

4. Identify the error in this DAX measure:

Measure = VAR TotalSales = SUM(Sales[Amount]) RETURN TotalSales * 0.1 VAR Tax = TotalSales * 0.1

medium

A. Variable names cannot have uppercase letters

B. RETURN keyword is missing

C. Variables must be defined before RETURN statement

D. SUM function cannot be used inside VAR

Solution

1. Step 1: Review variable and RETURN order

   In DAX, all VAR definitions must come before the RETURN statement.

2. Step 2: Identify misplaced VAR

   The variable Tax is defined after RETURN, which is invalid syntax.

3. Final Answer:

   Variables must be defined before RETURN statement -> Option C

4. Quick Check:

   All VAR before RETURN [OK]

Hint: Define all VAR before RETURN [OK]

Common Mistakes:

• Placing VAR after RETURN
• Ignoring syntax order rules
• Assuming RETURN can appear multiple times

5. You want to create a measure that calculates the average sales per customer but only for customers with sales above 500. Which DAX measure using VAR and RETURN is correct?

hard

A. Measure = VAR FilteredSales = FILTER(Sales, Sales[Amount] < 500) VAR AvgSales = AVERAGEX(FilteredSales, Sales[Amount]) RETURN AvgSales

B. Measure = VAR AvgSales = AVERAGEX(Sales, Sales[Amount]) VAR FilteredSales = FILTER(Sales, Sales[Amount] > 500) RETURN AvgSales

C. Measure = RETURN VAR FilteredSales = FILTER(Sales, Sales[Amount] > 500) VAR AvgSales = AVERAGEX(FilteredSales, Sales[Amount])

D. Measure = VAR FilteredSales = FILTER(Sales, Sales[Amount] > 500) VAR AvgSales = AVERAGEX(FilteredSales, Sales[Amount]) RETURN AvgSales

Solution

1. Step 1: Filter sales above 500

   VAR FilteredSales uses FILTER to keep only sales > 500, which matches the requirement.

2. Step 2: Calculate average sales on filtered data

   VAR AvgSales uses AVERAGEX on FilteredSales to get average sales per customer.

3. Step 3: Return the calculated average

   RETURN outputs AvgSales, the correct final result.

4. Final Answer:

   Measure = VAR FilteredSales = FILTER(Sales, Sales[Amount] > 500) VAR AvgSales = AVERAGEX(FilteredSales, Sales[Amount]) RETURN AvgSales -> Option D

5. Quick Check:

   Filter then average, return result [OK]

Hint: Filter first, then calculate average, then RETURN [OK]

Common Mistakes:

• Defining variables after RETURN
• Filtering sales less than 500 instead of greater
• Returning variable before defining it