What Is Power Query?
Power Query is Power BI's data cleaning and transformation tool, accessed via Transform Data. Real-world data is almost never ready to use straight away — inconsistent formatting, missing values, merged headers — and Power Query is where you fix all of that before it reaches your reports.
A useful mental model: Power Query is where you prepare the ingredients; Report view is where you cook the meal. Skipping proper prep makes everything downstream harder.
Common Cleaning Tasks
- Removing duplicates — Home → Remove Rows → Remove Duplicates
- Changing data types — click the type icon in a column header (text, whole number, date, etc.)
- Splitting columns — e.g. splitting "First Last" into two separate name columns
- Merging columns — combining City and State into one "Location" field
- Filtering rows — removing blanks, errors, or irrelevant categories before they hit your model
- Renaming columns — double-click a header to give it a clear, consistent name
Understanding Applied Steps
Every action you take in Power Query is recorded as a step in the Applied Steps panel on the right. This is one of Power Query's most powerful features — it's not just cleaning your data, it's recording a repeatable recipe.
That means next month, when you get a new export of the same report, you just refresh — Power Query re-runs every step automatically. You never have to redo the cleanup by hand.
Practical Tips
- Rename your steps (right-click → Rename) so your process is readable months later
- Fix data types early — most errors downstream trace back to a column being the wrong type
- Use "Remove Other Columns" rather than deleting the columns you don't need — it's clearer about intent
- Preview with a manageable sample; Power Query can feel slow on huge files while you're still experimenting