session login

signin. php

<?php
 session_start();
  header('Content-type: application/json');
 include 'config/koneksi.php';
$response = array();

		if($_POST){
			$nik             = mysqli_real_escape_string($conn,$_POST['nik']);
			$pass 			= md5($_POST ['password']);
		$sql = mysqli_query($conn, "SELECT karyawan.*,user.* FROM karyawan RIGHT JOIN user on karyawan.id_user=user.id_user where karyawan.NIP='$nik' and user.password='$pass' or user.email='$nik' and user.password='$pass'")or die (mysql_error());
        $data=mysqli_fetch_array($sql);
        $cek=mysqli_num_rows($sql);
           if($cek>=1){
			if($data['level']=="Management"){
				$response['status'] = 'success1';
				$_SESSION["management"]=$data['id_user'];


			}else if($data['level']=="Human Resource"){
				$response['status'] = 'success2';
				$_SESSION["human-resource"]=$data['id_user'];

			}else if($data['level']=="Employee"){
				$response['status'] = 'success3';
				$_SESSION["employee"]=$data['id_user'];

			}else if($data['level']=="Client"){
				$response['status'] = 'success4';
				$_SESSION["client"]=$data['id_user'];
			}
			else if($data['level']=="Guest"){
				$response['status'] = 'success3';
				$_SESSION["guest"]=$data['id_user'];
			}
			else if($data['level']=="General Affair"){
				$response['status'] = 'success3';
				$_SESSION["general-affair"]=$data['id_user'];
			}
			else if($data['level']=="Finance"){
				$response['status'] = 'success3';
				$_SESSION["finance"]=$data['id_user'];
			}
			else if($data['level']=="Intern"){
				$response['status'] = 'success3';
				$_SESSION["intern"]=$data['id_user'];
			}
			else if($data['level']=="Project"){
				$response['status'] = 'success3';
				$_SESSION["project"]=$data['id_user'];
			}

			else{
			 $response['status'] = 'error'; //
  			 $response['message'] = '<span>Your ID or password is wrong</span>';
			}

		}
		else{
			 $response['status'] = 'error'; //
  			$response['message'] = '<span>Your ID or password is wrong</span>';
		}

		}

  echo json_encode($response);

mysqli_close($conn);

logut.php

<?php
session_start();

include ("config/koneksi.php");

$username=$_GET['username'];

$online = mysqli_query($conn, "UPDATE user SET online = '' where username='$username'");
$online = mysqli_query($conn, "UPDATE follow SET online = '' where my_following='$username'");

unset($_SESSION['user']);
session_destroy();
header("location:login");
?>


index,php

<?php
  session_start();
  include "config/koneksi.php";
  if(isset($_SESSION['employee']) OR isset($_SESSION['management']) OR isset($_SESSION['human-resource'])
    OR isset($_SESSION['general-affair'])  OR isset($_SESSION['project']) OR isset($_SESSION['intern']) OR isset($_SESSION['client']) OR isset($_SESSION['guest']) OR isset($_SESSION['finance'])){




?>

hello world

<?php

   }else{
    header("location:login");
}
?>