Suppose you want sales by:
Region + Product
You could get:
Region Product Total Sales
West Laptop 120,000
West Monitor 25,000
South Laptop 60,000
South Monitor 30,000
This can be useful when preparing summary datasets for specific reporting requirements.
6. When Should You Use Group By?
Group By is useful when you genuinely need a summarized table.
For example, imagine a source contains 10 million transaction records but another process only needs:
Region
Month
Total Sales
You may be able to create a summarized dataset containing only those required values.
However, don't automatically summarize everything in Power Query.
If your Power BI model needs transaction-level detail for interactive analysis, removing that detail too early can prevent you from performing analyses later.
Always ask:
"Do I need the individual records later?"
7. A Practical Example
Imagine you receive transaction data containing:
Customer Region Amount
Rahul West 80,000
Priya South 25,000
Amit West 75,000
Sneha North 15,000
Karan West 40,000
You could use Power Query to:
Step 1 — Create a customer category
Using a Conditional Column:
Amount >= 75,000 → High Value
Amount >= 25,000 → Medium Value
Otherwise → Low Value
Step 2 — Create another calculation
Using a Custom Column:
Adjusted Amount = Amount * 1.10
Step 3 — Create a regional summary
Using Group By:
West → ₹195,000
South → ₹25,000
North → ₹15,000
You've now used three different Power Query capabilities for three different purposes.
⚠️ Common Beginner Mistake
A common mistake is creating every possible calculation as a Custom Column.
For example, you might calculate:
Total Sales
Average Sales
Sales Growth
Profit Margin
as physical columns in Power Query.
That's not always the right approach.
Some calculations are better created as DAX measures, especially calculations that need to respond dynamically to filters and user selections.
You'll learn the difference between Power Query calculations and DAX calculations in much greater detail later.
🎯 Practical Exercise
Take a sales dataset and try to create:
Conditional Column
Create:
Sales Category
with:
= 50,000 → High
= 20,000 → Medium
< 20,000 → Low
Custom Column
Create:
Total Amount
using:
Quantity × Price
Group By
Calculate:
Total Sales by Region
Then inspect the Applied Steps pane and see how Power Query records each operation.
💡 Key takeaway
Conditional Columns help you classify data.
Custom Columns help you create values using expressions.
Group By helps you summarize data.
Understanding when to use each one is more important than simply knowing where the buttons are.
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