erro foreach

<?php
var_dump($_POST['num']);
$message = "";
if(isset($_POST['enviaformulario'])){ //check if form was submitted
  $db_connect = MySql::conectar();
        //<-- user information register start -->
        $user_name = $_POST['user_name'];
        $user_mail = $_POST['user_email'];
        $user_phone = $_POST['user_phone'];
        $cost = $_POST['total_cost'];
        $cost = (float)$cost;
        $user_sql = "INSERT INTO `tb_site.user` (`name`,`email`,`phone`,`total_cost`) VALUES ('". $user_name ."','". $user_mail ."','". $user_phone ."',". $cost .")";
        $db_connect->query($user_sql);
        $user_id = $db_connect->lastInsertId();
        //<-- user information register end-->
        $number_list = $_POST['num'];
        $rifa_id = intval($_POST['rifas_id']);
        $number_type = 1;
        $number_list = "";
        foreach($number_list as $num){
            $num = intval($num);
            $sql = "INSERT INTO `tb_site.test`(`rifas_id`,`number`,`type`,`user_id`,`cost_id`) VALUES (".$rifa_id.",".$num.",".$number_type .",". $user_id.",".$rifa_id.");";
            $db_connect->query($sql);
        }
  $mensagem = "Sucesso.: ".$input;
}
?>

<html>
<body>
<form action="" method="post">
<?php echo $mensagem; ?>

  <input type="submit" name="enviaformulario"/>
</form>
</body>
</html>