I can't speak for anyone else as I don't and have NEVER used W3Schools for anything related to PHP or MySQL but used PHP's manual and MySQL docs for anything, b

I can't speak for anyone else as I don't and have NEVER used W3Schools for anything related to PHP or MySQL but used PHP's manual and MySQL docs for anything, but when someone needs help and asks me, I usually use my experience and write up a quick example and do not go through the whole sanitizing of inputs and that, as they're just an example and sometimes are written right on the spot but I do let them know it's only an example and not to be copy and pasted into their documents and that they should properly secure their stuff with input sanitization.