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'];

$selr=$connection->query("SELECT subcategoryname FROM busdir_mst_subcategory WHERE subcategoryname='".$subcategoryname."' AND catid = $catid");
if($selr->num_rows!=0)echo "Duplicate Subcategory Name";
else{
	$addq="INSERT INTO busdir_mst_subcategory(subcategoryname,catid,createdby,createdon) VALUES('$subcategoryname',$catid,'".$_SESSION['company_id']."',NOW())";
	$addr=$connection->query($addq);
	if($addr)echo "success";
	else echo "An unknown error occured. Please try again.";
}
$selr->free();
$connection->close();
?>