Get data from Database to Chart

Hey, any help with this would be greatly appreciated!

I am trying to display data collected from a form using Chart.js. The data is for a students result on an exam created by the user. The user creates an exam, then can add results for all students created by that user, meaning there is not a set number of students at any point. I want to then take these entered results and display them as a bar chart, showing each students result for the exam but I don't know where to start.