if(isset($_POST['r_submit'])) {

$r_username = mysql_real_escape_string($_POST['r_username']);
$r_password = mysql_real_escape_string($_POST['r_password']);
$r_repeat_password = mysql_real_escape_string($_POST['r_repeat_password']);
$r_email = mysql_real_escape_string($_POST['r_email']);

if(!empty($r_username) && !empty($r_password) && !empty($r_repeat_password) && !empty($r_email)) {

	if($r_password === $r_repeat_password) {
		$query = "INSERT INTO users(username, password, email) VALUES('$r_username', '$r_password', '$r_email'";

		$result = mysql_query($con,$query);

			if($result) {
				echo "Succesfully registered";
			}
			else {
				echo "An error occured while registering";
			}
	}
	else {
	echo "Passwords do not match!";
	}
}
else {
echo "Je moet alle velden invullen";
}
}


CONNECTION.PHP

$host = 'localhost';
$username = 'root';
$password = 'usbw';
$database = 'database';
$con = (mysqli_connect('localhost','root','usbw','database'));

if(!$con) {
echo "An error occured";
exit;
}