This is the finished tutorial from the Board to Bits SQL Unity Tutorial.
I noticed people got stuck at the user login / password check (part 4 of the tutorial), so hopefully my finished project can help those in need. My long dumb explanation / reasoning is in the comments section as well, so read that if you're confused. It is possible I might've went overboard and it was probably a spacing error in the PHP file, but it is what it is. I didn't do all of tutorial from part 6, which was doing finishing touches. It isn't too important and isn't game breaking. This was done in Unity 2018.1.3.1f1. Board to Bits was in Unity 2017, so my guess that version change caused problems, maybe. The problem really was in my PHP file, so probably not. ¯\_(ツ)_/¯
I made a small leaderboard / high scores thing as a small exercise for myself. If you wanted to do that but got stuck, you can take a look on how I approached it. It only does the top 5, but it is a good start. There are a lot of questions I have about PHP because this is my first time using PHP, so I'm not familiar with certain conventions and nuances of the language. I also added a feature where if there aren't at least 5 people in the table, it will insert 5 "random" people into the table. I did change some things around in the C#/Unity side, so you might need to poke around if you are looking at it. But the php files should, for the most part, be close to the tutorial. I did change some variable name conventions because it was confusing me without some sort of marker in variable names(ie: varname vs var_name). Again, not sure if that's the "standard" or what-not.