<?php
     require 'database-config.php';
     session_start();
     $username="";
     $password="";
    if($SERVER["REQUEST_METHOD"]=="POST")
    {
    $username=mysqli_real_escape_string($con,$_POST['username'];
    $password=mysqli_real_escape_string($con,$_POST['password'];
     $role ="SELECT 'email' FROM users WHERE email='$username' AND  password='$password'";
    $result = mysqli_query($con,$role);
    $row=mysqli_fetch_array($result,MYSQLI_ASSOC);
    $count = mysqli_num_rows($result);
    //check user is registered user
    if(count==1)
    {
    // registered user position
     $position = mysqli_query($con,"SELECT role FROM users WHERE       username='".$_SESSION['username']."'");
    $field = mysqli_fetch_all($position,MYSQLI_ASSOC);
    echo "wel come:".$field;
    }
    else{
     echo 'you are not registered user';
    }
   }
   ?>