New to WordPress: How to Build XLS from Database?

Hi there, I don’t know anything about WordPress except how to install it, and my client would like a link from a WordPress page to allow users to download a spreadsheet built from database data. I know how to do this technically, but I don’t know how to do it to stay within WordPress standards. Is there a reference or something? Would the link be another template? Is a plug-in involved? I’m not sure the direction to take.

I can’t spend my client’s money learning WordPress, so I may just end up writing this as a PHP page outside of WordPress unless the solution is fairly straightforward. It’s the approach that I don’t know. I’ve spent 45 minutes trying to find an example of how to do something like this but haven’t found anything, and I’m afraid I’ll have to give up soon and go the usual route instead.

Thanks for your help, all!