Check if background image is set - php

Question

I'm working on a simple script - file input which will change the site's background to the given image. It works, but my problem starts when I refresh site - the background image disappears.
I was wondering how to set and check if the background was set, so it will be there as long since next file input ?
I was trying to do that with a constant but does not work, here is my code:
if (isset($_POST['submit_bgImg'])) {
$myTarget = 'img/' . basename($_FILES['bg_img']['name']);
if (move_uploaded_file($_FILES['bg_img']['tmp_name'], $myTarget)) {
print('<style> body {background-image:url(img/' . $myFile . ');}</style>');
define('MY_BG', $_FILES['bg_img']['name']);
}
}
if (defined('MY_BG')) {
print('<style> body {background-image:url(img/' . MY_BG . ');}</style>');
}
any help ?

Answer 1

If you want to keep it only for the user you must store MY_BG variable in Session or Cookies like :$_SESSION['my_bg'] = $_FILES['bg_img']['name'];
if you want to keep it forever you must store it on a file or a Database like MySQL
$conn = new MySQLi('host','user','password','database name');
$conn->query("INSERT INTO table VALUES ('" . $bg_name . "')");

Answer 2

Try out with echo in php instead of print.I recommended to you can use ajax.
if (isset($_POST['submit_bgImg'])) {
$myTarget = 'img/' . basename($_FILES['bg_img']['name']);
if (move_uploaded_file($_FILES['bg_img']['tmp_name'], $myTarget)) {
echo "<style> body {background-image:url(img/' . $myFile . ');}</style>";
define('MY_BG', $_FILES['bg_img']['name']);
}
}
if (defined('MY_BG')) {
echo "<style> body {background-image:url(img/' . MY_BG . ');}</style>";
}