Over the past two parts I have explained what I am planning to do in this tutorial and have shown you how to create a database to use with the tutorial.
In this part I will be showing you how to insert some information into your database so that it is more useful.
To demonstrate, the following will produce the result 6: String concatenation in My SQL requires the CONCAT() function so there is no ambiguity here and My SQL converts the strings to floats and adds them together.
I actually think the reason the initial query wasn't working is most likely because the $points variable was not in fact set to the user's current points.
thank you @Steve your comment might sound clever for someone who knows what PDO is, but for me who's just diving into PHP/My SQL, it doesn't really shine a lot of light into the matter. If so, please edit the answer or post one of your own where you show how it's better with PDO.