错误的电子邮件或密码通知/警报

Question

因此，在用户成功登录到他/她的帐户后，他/她应该被定向到index.php并且Chrome在右上方显示了这个微小的通知

但是，当用户输入错误的电子邮件或密码时，Chrome在图片中也会显示相同的通知，但当然，他/她不会重定向到index.php。我怎么能告诉＆＃34;该用户输入错误的电子邮件/密码的Chrome /用户？

$email = mysqli_real_escape_string($mysqli, $_POST["email"]);
$password = mysqli_real_escape_string($mysqli,$_POST["password"]);

//select all data by using email and password entered
$customers = $mysqli->query("select * from customer where CustomerEmail='".$email."' and CustomerPassword='".$password."'");
$customer = mysqli_num_rows($customers);

$managers = $mysqli->query("select * from manager where ManagerEmail='".$email."' and ManagerPassword='".$password."'");
$manager = mysqli_num_rows($managers);

$staffs = $mysqli->query("select * from staff where StaffEmail='".$email."' and StaffPassword='".$password."'");
$staff = mysqli_num_rows($staffs);

echo $customer.'<br>';
echo $manager.'<br>';
echo $staff.'<br>';

    //if customer is true
    if($customer== 1){
        $row = mysqli_fetch_assoc($customers);
        $id= $row['CustomerID'];
        $email = $row['CustomerEmail'];
        $name = $row['CustomerName'];

        //start session
        session_start();
        //create session
        $_SESSION['CustomerID'] = $id;
        $_SESSION['CustomerEmail'] = $email;
        $_SESSION['CustomerName'] = $name;

        //redirect page to index.php    
        header("Location: index.php");
        }

    //if manager is true
    else if($manager == 1){
        $row = mysqli_fetch_assoc($managers);
        $id = $row['ManagerID'];
        $email = $row['ManagerEmail'];
        $name = $row['ManagerName'];

        //start session
        session_start();
        //create session
        $_SESSION['ManagerID'] = $id;
        $_SESSION['ManagerEmail'] = $email;
        $_SESSION['ManagerName'] = $name;

        //redirect page to managerCP.php
        header("Location: managercp.php");
        }

    //if staff is true
    else if($staff == 1){
        $row = mysqli_fetch_assoc($staffs);
        $id = $row['StaffID'];
        $email = $row['StaffEmail'];
        $name = $row['StaffName'];

        //start session
        session_start();
        //create session
        $_SESSION['StaffID'] = $id;
        $_SESSION['StaffEmail'] = $email;
        $_SESSION['StaffName'] = $name;

        //redirect page to staffCP.php
        header("Location: staffcp.php");
        }

    //if all condition is false 
    else    {
//alert will be appeared

echo '<script language="javascript" type="text/javascript">alert("The combination of email and password do not match");document.location.href="index.php"</script>';
//header ("Location:index.php");
}

好。所以警报有效，但问题是显示白屏，我必须点击＆＃34;确定＆＃34;在重定向回index.php之前。我希望警报出现在index.php上。帮助