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Power Query

Intermediate
14 min

What is Power Query?

Power Query transforms and cleans data before loading to Power BI, handling data preparation tasks automatically.

Key Components:

  • Cleans and transforms data
  • Combines multiple sources
  • Records transformation steps
  • Uses M language

Why it matters

Data Cleaning

Remove errors, handle missing values

Combine Files

Merge multiple Excel files

Transform Data

Change formats, add columns

Reusable Steps

Apply same transformations

Key Concepts

Applied Steps

Recorded transformations

Example: Each action is a step...

M Language

Power Query formula language

Example: = Table.SelectRows()...

Merge

Combine queries like SQL JOIN

Example: Merge Sales and Products...

Append

Stack rows from multiple queries

Example: Jan Sales + Feb Sales...

How to use

1

Get Data

Select data source

2

Transform

Remove columns, filter rows

3

Change types

Set correct data types

4

Add columns

Create calculated columns

5

Group/Summarize

Aggregate data

6

Load to model

Load transformed data

Example

Goal: Clean sales data
Remove blank rows
Change date to Date type
Replace nulls with 0
Add Total column
Result: Clean, analysis-ready dataset

Pro Tips

  • •Rename steps: Keep transformations readable
  • •Use Group By: For aggregation
  • •Reference queries: Avoid duplication

Practice

Combine monthly sales files into a single clean table
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