OverLord Shell

<?php 
error_reporting(0);
session_start();
if(!isset($_SESSION['company_id']) || !isset($_SESSION['company_name'])){session_destroy();echo "login.php";exit;}
if(!in_array(6,$_SESSION['role'])){echo "404.php";exit;}
if($_SERVER['REQUEST_METHOD']!='POST' || empty($_POST)){echo "404.php";exit;}
require_once("../db/conn.php");

$subcategoryname=htmlentities($_POST['subcategoryname'],ENT_QUOTES);
$catid=$_POST['catid'];
$subcatid=$_POST['subcatid'];

$selr=$connection->query("SELECT subcategoryname FROM busdir_mst_subcategory WHERE subcategoryname='".$subcategoryname."' AND catid != $catid");
if($selr->num_rows!=0)echo "Duplicate Subcategory Name";
else{
	 $updateq="UPDATE busdir_mst_subcategory SET subcategoryname = '$subcategoryname',catid = '$catid',modifiedby='".$_SESSION['company_id']."' WHERE subcatid=".$subcatid;
	$updater=$connection->query($updateq);
	if($updater)echo "success";
	else echo "An unknown error occured. Please try again.";
}
$selr->free();
$connection->close();
?>