How to take updated data from the database?

Question

PHP

There is a color upgrade code

include ('../connect/config.php');
  
if (isset($_POST['update_color'])){
$id=$_SESSION['id'];
$site_color = $_POST['site_color'];
$sql = ("UPDATE users SET site_color='$site_color' WHERE id='$id'");
$query = mysql_query($sql);
if (!$query){
die('updating error'. mysql_error());
}
else { echo 1; }
}
header('Location: /');

How to make it so that after updating the data in the database, this updated data is displayed on the page?
And then they are updated when you go to the site

Answer 1

I'm not a strong specialist in terms of code here, but ...
When executing update_color before querying the database (or after), force the user to reload the page (if it's not critical, which is long), or change the required block in CSS in the browser with Javascipt.

Answer 2

Your code is unsafe.
Imagine your code where $_POST['site_color'] = "123', username=(DELETE Users), id=1";

$site_color = $_POST['site_color'];
$sql = ("UPDATE users SET site_color='$site_color' WHERE id='$id'");