Untitled

<?php
session_start();
$mysqli=new MySQLi("localhost", "root", "", "hws");
$role="";

$username=filter_input(INPUT_POST, 'username', FILTER_SANITIZE_STRING);
$password=filter_input(INPUT_POST, 'password', FILTER_SANITIZE_STRING);

if($query=$mysqli->prepare("SELECT `role` FROM members WHERE username=? AND password=?"))
{
    $query->bind_param("ss", $username, $password);
    $query->execute();
    $query->bind_result($role);
    $query->fetch();
}
else
{
    echo "Errors in the Query. ".$mysqli->error;
    die();
}

    if($role!="")
    {
        $_SESSION['ingelogt']=$username;
        $_SESSION['user_role']=$role;
        $location="$role.php"; // If role is admin this will be admin.php, if student this will be student.php and more.
        header("location: $location"); // Redirect to the respective pages.
    }
    else
    {
        echo "Invalid password, username combination";
    }

?>

<?php
session_start()
if(!isset($_SESSION['ingelogt']))
{
    header("location: index.php"); // The user is not logged in. Redirect him to the login page.
}

$page_role="leerling"; // This must be admin for admin.php and student for student.php and similar

$role=$_SESSION['user_role'];

if($role!=$page_role) // If student come to admin page by mistake or admin to student and similar
{
    echo "You are not supposed to be here.";
    die();
}
?>
<!DOCTYPE html>
<html>
    <head>
        <title>Home</title>
        <link rel="stylesheet" href="css/style.css">
        <link rel="stylesheet" href="css/fontello.css">
    </head>

    <body>
        <div class="siteContainer">
            <div class="navLeft">
                <a href="overzicht.php">
                    <img src="../../img/logo.png" alt="HWSysteem" class="mainLogo">
                </a>
            </div>
        </div>
    </body>
</html>

<?php
session_start();
$mysqli=new MySQLi("localhost", "USER_NAME_HERE", "PASSWORD_HERE");
$role="";

$username=filter_input(INPUT_POST, 'username', FILTER_SANITIZE_STRING);
$password=filter_input(INPUT_POST, 'password', FILTER_SANITIZE_STRING);

if($query=$mysqli->prepare("SELECT `role` FROM members WHERE username=? AND password=?"))
{
    $query->bind_param("ss", $username, $password);
    $query->execute();
    $query->bind_result($role);
    $query->fetch();
}
else
{
    echo "Errors in the Query. ".$mysqli->error;
    die();
}

    if($role!="")
    {
        $_SESSION['ingelogt']=$username;
        $_SESSION['user_role']=$role;
        $location="$role.php"; // If role is admin this will be admin.php, if student this will be student.php and more.
        header("location: $location"); // Redirect to the respective pages.
    }
    else
    {
        echo "Invalid password, username combination";
    }

?>

And in your admin.php, student.php

<?php
if(!isset($_SESSION['ingelogt']))
{
    header("location: login.php"); // The user is not logged in. Redirect him to the login page.
}

$page_role="admin"; // This must be admin for admin.php and student for student.php and similar

$role=$_SESSION['user_role'];

if($role!=$page_role) // If student come to admin page by mistake or admin to student and similar
{
    echo "You are not supposed to be here.";
    die();
}

?>