I am working on a teachers grading system project. Students will assign positive and negative grades to teacher. For this purpose there should be a list of teachers, and for each teacher I want to use two radio buttons for grading. When students click the first radio button there should be an increment in an integer value of grades of that specific teacher and when they click the other radio button there should be a decrement. I want code using php and mysql. I have no idea how to do this at all.
Assuming you have a teachers table that has a field for grades, I would suggest to use AJAX to acheive what you want to do. Since you didn't post any code or you haven't started yet, I would suggest you to take a look at this tutorial:
http://phppot.com/jquery/php-voting-system-with-jquery-ajax/