Script Login

<?php
session_start();
include "connection.php";


    $username   = $_POST['user'];
    $password   = $_POST['pass'];
    $pass=md5($password);

    $kueri=mysqli_query($connection,"SELECT * FROM pemilikkost WHERE username='$username' AND password='$pass'");
    if(mysqli_num_rows($kueri) == 0)
    {
        $kueri1=mysqli_query($connection,"SELECT * FROM member WHERE username='$username' AND password='$pass'");
        $row1=mysqli_fetch_array($kueri1);
        $user1 = $row1['username'];
        $pass2 =$row1['password'];
        $n1=$row1['id_member'];
        $n2=$row1['nama_lengkap'];

        if ($username == $user1 && $pass == $pass2) {
            $_SESSION['login'] = true;
            $_SESSION['username'] = $user1;
            $_SESSION['id_member'] =$n1;
            $_SESSION['nama_lengkap'] =$n2;

            header("location:Member/index.php");
        }else{
                $kueri3=mysqli_query($connection,"SELECT * FROM admin WHERE username='$username' AND password='$pass'");
                $row3=mysqli_fetch_array($kueri3);
                $user1 = $row3['username'];
                $pass2 =$row3['password'];

                    if ($username == $user1 && $pass == $pass2) {
                        $_SESSION['login'] = true;
                        $_SESSION['username'] = $user1;
                        header("location:Admin/index.php");
                    }
             }
    }else
    $kueri=mysqli_query($connection,"SELECT * FROM pemilikkost WHERE username='$username' AND password='$pass'");
    $row4=mysqli_fetch_array($kueri);
    $user1 = $row4['username'];
    $pass2 =$row4['password'];
    $namapk =$row4['nama_pk'];

        if ($username == $user1 && $pass == $pass2) {
            $_SESSION['login'] = true;
            $_SESSION['username'] = $user1;
            $_SESSION['nama_pk'] = $namapk;
            header("location:User/index.php");
        }else{
            echo "<script>alert('Username atau Password Anda Salah')
        window.location ='index.php';</script>";
        }

?>