how to create a progress bar using php output buffering and jquery?

i been searching this for weeks,

i am desperate to learn this, this is a very big help for me, is someone the here share some codes?

i know the this will need to script. i have tried sereval code for my client side script:

var request = new XMLHttpRequest();
request.addEventListener("progress", updateProgress, false);

function updateProgress(e) {
var percent = (e.loaded / e.total) * 100;
 /** update the with of the progress bar **/
}

and to my server side, i dont know how. but actually i want to use this for a mysql query so that i can see the progress of my query and another thing is i dont know how to use output buffering.

somebody help me on this please.