How it works:
First, we concat a '/' to the end of the URL, just in case there is none there already.
Then we replace 'http://' and 'https://' and 'www.' with nothing.
That gets us down to something like codingforums.com/gobbledygook/
So then we use LOCATE to find the first '/' in that (which MIGHT be the one we added at the first step).
And then we use SUBSTR to get all the characters up to but not including that first '/'.
An optimist sees the glass as half full.
A pessimist sees the glass as half empty.
A realist drinks it no matter how much there is.