Handling “Duplicate” Query String Values with Power Query

Chris Webb troubleshoots an issue:

Some time ago I wrote a pair of popular posts about using the Query and RelativePath options of the Web.Contents function in Power Query and why they are important for dataset refresh. I have recently learned something extra about this subject which merits a new post, though: how to handle multiple URL query parameters with the same name.

It’s interesting to see how Power Query handles this, as there’s no defined standard behavior. Some renderers give you just the first item, some just the last, and some (like IIS + .NET) give you back a list of all items when you have a query string like ?param1=x&param1=y&param1=z.