Multiple value

//--ASALNYA :
$id_siswa ='$_GET[id_siswa]';
$result = mysql_query("SELECT id_siswa, hobi
                                   FROM tb_siswa
                                   WHERE id_siswa='$id_siswa'");
$array = mysql_fetch_array($result);

$sql=mysql_query("SELECT * FROM ms_hobi");
while($row=mysql_fetch_assoc($sql)){
$list_id = explode(",",$array['hobi']);
$id = $row['id_hobi'];

foreach ($id as $hobi) {
    if(in_array($id, $hobi)){
        echo '<option value="'.$id.'" selected>'.$row['hobi'].'</option>';
            }   else {
        echo '<option value="'.$id.'">'.$row['hobi'].'</option>';
    } } }

//-- DIUBAH MENJADI:
//--
$id_siswa =$_GET[id_siswa];
$result = mysql_query("
    SELECT hobi
    FROM tb_siswa
    WHERE id_siswa='$id_siswa'
");
$array = mysql_fetch_assoc($result);
$list_id = explode(",",$array['hobi']);
$sql=mysql_query("SELECT * FROM ms_hobi");
while($row=mysql_fetch_assoc($sql)){
    echo "<option value='{$row['id_hobi']}'".(in_array($row['id_hobi'], $list_id)?" selected":"").">{$row['hobi']}</option>";
}
//--