Power Query is a very powerful extension and requires more attention. So, for today, I have decided how to write and use a custom formula. It will be a simple example to show friendly name of the months based on month’s numbers.

Let’s imagine we have this data.
And now we want to show friendly name of the month for each date in the “Start Date” column. Of course we can use some VBA formulas as well, but let’s use something more modern. Just go to “Power Query” ribbon to create a blank query, which will contain our custom formula.Actually the sequence is: Power Query -> Get External Data -> From Other Sources -> Blank Query. We name the query “ShowMonthName” and in Advanced Editor we enter the formula (to enter in the editor respect the sequence: “Home” ribbon -> “Query” tab -> “Advanced Editor” button).
Custom formula
What we actually did? We create a formula called “ShowMonthName” which can be used in Power Query connection. And I am going to show how to do this.

Place mouse inside used range containing dates and do the following: Power Query -> Excel Data -> From Table. Excel will select by default entire used range, so you probably do not need to adjust it and you can go to the next screen, which is our query editor window. Here you go to Add Column tab and click on Add Custom Column button from General tab. And for the next step you need to name your column and insert our formula in formula text area control. This is straight forward and there no other explanation needed.
Add custom column
If everything is correct, you will see the results immediately in the query editor window and, if there is no error, you can use the connection you have just created, which includes the custom formula.
Formula results
I really encourage you to start using Power Query. It will open a new world for you and you will love using it, because it is a step forward in reporting and business intelligence. Leave behind ugly VBA formulas and start looking for the future.