Power Query Editor Basics

Reading Time: 8 Mins | Level: Beginner to Advanced

1. What is Power Query?

Power Query is the ETL (Extract, Transform, Load) engine inside Power BI. Every transformation step you perform (e.g. removing columns, filtering rows, replacing values) is recorded sequentially in the Applied Steps pane using Microsoft's functional language: M.

2. Applied Steps: The Non-Destructive Recipe

Unlike Excel where deleting a column permanently modifies your original data file, Power Query is non-destructive:

• The source file remains completely untouched.
• Power Query builds an executable script of transformations.
• During every data refresh, Power Query re-executes each step in exact order.

3. The Power Query Ribbon

• Home: Split column, Group By, Merge Queries, Append Queries.
• Transform: Modifies existing columns in place (e.g. uppercase, math, transpose).
• Add Column: Creates a new column while preserving the original column (e.g. Custom Column, Conditional Column).