It’s a good question for newbies to have, where to start?
What comes first PHP or MySQL? The chicken or the egg?
You can learn both independently, but if you have no experience with either, I think it’s best to start with PHP. Pretty quickly as you work through tutorials you will encounter MySQL. They really go hand in hand for many applications.
If you have zero experience, there are other things you will need to learn also if you haven’t already…