使用PHP面向对象编程简单更新MySQL

I am doing an update into mysql but would like to do this in OOP instead of the procedural method. How can I update with OOP? I am first testing that there is data to update in the input. Check to see if it is empty. Then I take that result and store it into a variable and then I query the database to update the column, I then submit the image file to the correct folder. Below is the code I am working with. I keep getting a blank page. I don't get any error messages to see where I am going wrong. I have tried a few different modifications but none are working. I am doing an update into mysql but would like