You can add comments to your code either with single-line comments that start with ‘//’ or multi-line comments that start with ‘/*’ and end with ‘*/’. Comment plays an important role to understand the code. In the future, if you want to change some part of code or want to share your code with your friend, who can easily understand code without your help then comment in code is important.
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Data Analytics Tricks in Power BI – Guidebook
You too can analyze data like a Data Scientist. No coding needed. No statistics needed.
Analyze & Visualize data using Power BI. (23 tricks in one book)
Adding Comments In M With Power Query
Let’s take an example to see how it works.
Step 1: Load Data in Power Query
Load the data in Power Query first to apply comments in M as shown below. Perform some action to the data table loaded in Power Query. Here we have merged the columns.

Step 2: Open Advanced Editor
To open Advanced Editor in Power Query click on
Home > Advanced Editor

Step 3: Add Comments in M
Add a single comment to the query for merging columns in the Advanced Editor dialogue box as shown below. We have added the comment //Merge Columns to the Advanced Editor.

Step 4: Close & Apply
The picture below shows the data table after merging the columns and adding comments in Query Editor. Now you can close and apply the changes.

Data Analytics Tricks in Power BI – Guidebook
You too can analyze data like a Data Scientist. No coding needed. No statistics needed.
Analyze & Visualize data using Power BI. (23 tricks in one book)