Power Query is the place where you clean and prepare your data before it is used for analysis or dashboards.
Every Power BI assignment begins in Power Query.
This is where you fix the data so that your report results come out correctly.
1. Open Power Query
After you import your dataset into Power BI:
On the top menu, click Home
Click Transform Data
Power Query Editor will open in a new window
This is where all cleaning steps happen
2. Understand What You See
In Power Query, you will see:
Area | What It Shows |
Data Preview (middle area) | Your actual dataset rows and columns |
Queries (left side) | Each table or file you are working on |
Applied Steps (right side) | Every transformation you perform |
Everything you do gets recorded under Applied Steps.
This means:
You do not need to memorize anything
You can undo any step anytime
3. Common Cleaning Steps You Will Use
Your assignments will usually require:
Task | Example Action |
Rename columns | To make them more meaningful |
Remove extra columns | To keep only what matters |
Change data types | Text → Number, Number → Date |
Split columns | Example: Full Name → First Name + Last Name |
Filter rows | Remove blanks or unwanted values |
Merge queries | Combine two tables using a matching field |
Append queries | Stack tables with similar structure |
These steps are learned by practicing — not memorizing.
4. Apply Transformations Slowly
Do one step at a time:
Make one cleaning change
Check if your data looks correct
Move to the next step
There is no rush.
The goal is clarity, not speed.
5. When You Are Done Cleaning
Click:
Close & Apply
Your cleaned data will now load into Power BI for modeling.
Power Query is now complete for this assignment.
6. If You Make a Mistake
No problem.
You can:
Delete a step in Applied Steps
Or restart from the raw file
Power Query is safe — it never changes your original data file.
7. Expected Output After Power Query
When your cleaning is finished, your table will:
Have meaningful column names
Have correct data types
Contain only the data you need
Be ready for Data Modeling (next step)
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