I'm trying to display specific mysql table value based on two variables php

I'm trying to display specific mysql table value based on two variables php

First of all, I am new to php and objective c. I am making an iOS app in
Xcode and I'm trying to display the points that are specific to each
customer. Right now in phpmyadmin, I have 3 tables in 1 database. The
tables are testt (which contains each business name and other
information), customers (which contains each customers' information), and
rewards_points (which contains a two columns to connect with the other two
columns and a points column).
You don't have to give any code (although it would probably be more
helpful). I just want to know how to get specific points based on the
customer id and the business id and display it in Xcode. I think this
would be accomplished in the php file connecting to the Xcode project
since it is where the data is organized.
Thanks in advance!