Update query loopt fout ??

<?php
include 'connect.php';
function add($string) {
    $string=mysql_real_escape_string($string);
    return $string;
}
function strip($string) {
    $string=stripslashes($string);
    $string=htmlspecialchars($string);
    return $string;
}
$qry="SELECT * FROM ".$_GET["tabel"];
if ( !($result = mysql_query($qry)) ) {
    echo "Error: ".mysql_error();
}
else {
    if ($_SERVER['REQUEST_METHOD'] == "POST") {
        $error=0;
        $goed=0;
        while (list($key, $val) = each($_POST)) {
            if ($key != "submit_edit") {
                if (!mysql_query("UPDATE ".$_GET['tabel']." SET ".$key." = ".add($val)." WHERE id = ".$_GET['id'])) {
                    echo "Error: ".trigger_error(mysql_error());
                    $error++;
                }
                else {
                    $goed++;
                }
            }
        }
        if ($error==0) {
            echo 'Succesvol ge-update!!';
            echo '<meta http-equiv="refresh" content="2; URL=edit.php?tabel='.$_GET["tabel"].'&id='.$_GET["id"].'" />';
        }
        else {
            echo 'Er is een error opgetreden.';
            echo '<br />Er zijn '.$goed.' Query\'s gelukt.';
        }
    }
    else {
        echo '<form action="edit.php?tabel='.$_GET["tabel"].'&id='.$_GET["id"].'" method="POST">';
            $i=0;
            $a=0;
            $fields=mysql_num_fields($result);
            while ($i != mysql_num_fields($result)) {
                $field_names = array();
                $field_type = array();
                while ($i != mysql_num_fields($result)) {
                    $field_names[] = mysql_field_name($result, $i);
                    $field_types[] = mysql_field_type($result, $i);
                    $i++;
                }
                echo '<table style="width: auto; margin: 0px auto; margin-top: 40px;">';
                    foreach ($field_names as $field_name) {
                        $Qry=mysql_query("SELECT ".$field_name." FROM ".$_GET["tabel"]." WHERE id = ".$_GET["id"]) or die (mysql_error());
                        while ($row=mysql_fetch_assoc($Qry)) {
                            echo '<tr>';
                                echo '<th align="left" valign="top">'.$field_name.'</th>';
                                if ($field_name == "album") {
                                    echo '<td>';
                                        $qrY=mysql_query("SELECT * FROM album") or die (mysql_error());
                                        echo '<select name="'.$field_name.'">';
                                            while ($rijtje=mysql_fetch_assoc($qrY)) {
                                                if ($rijtje["id"] == $row[$field_name]) {
                                                    echo '<option value="'.$rijtje["id"].'" selected="selected">'.$rijtje["naam"].'</option>';
                                                }
                                                else {
                                                    echo '<option value="'.$rijtje["id"].'">'.$rijtje["naam"].'</option>';
                                                }
                                            }
                                        echo '</select>';
                                    echo '</td>';
                                }
                                elseif (mysql_field_type($result, $a) != "blob") {
                                    echo '<td><input type="text" name="'.$field_name.'" value="'.strip($row[$field_name]).'"></td>';
                                }
                                else {
                                    $row[$field_name]=str_replace("<br />", "\n\r", $row[$field_name]);
                                    echo '<td><textarea name="'.$field_name.'" cols="70" rows="10">'.strip($row[$field_name]).'</textarea></td>';
                                }
                            echo '</tr>';            
                        }
                        $a++;
                    }
                    echo '<tr>';
                        echo '<td><a href="index.php?page=edit&delete=ja&tabel='.$_GET["tabel"].'&id='.$_GET["id"].'" onclick="javascript: return confirm(\'Weet je zeker dat je deze waarde wilt wissen?\')"><input type="button" class="submit" name="wissen" value="wissen"></a></td>';
                        echo "<td><input type='submit' class='submit' name='submit_edit' value='opslaan'></td>";
                    echo '</tr>';
                echo '</table>';
            }
        echo '</form>';
    }
}
?>

<form action="edit.php?tabel=foto&id=1" method="POST">
    <table style="width: auto; margin: 0px auto; margin-top: 40px;">
        <tr>
            <th align="left" valign="top">id</th>
            <td><input type="text" name="id" value="1"></td>
        </tr>
        <tr>
            <th align="left" valign="top">album</th>
            <td>
                <select name="album">
                    <option value="1" selected="selected">Marille</option>
                </select>
            </td>
        </tr>
        <tr>
            <th align="left" valign="top">titel</th>
            <td><input type="text" name="titel" value="Test"></td>
        </tr>
        <tr>
            <th align="left" valign="top">naam</th>
            <td><input type="text" name="naam" value="1248025619IMG_4611.JPG"></td>
        </tr>
        <tr>
            <th align="left" valign="top">beschrijving</th>
            <td><textarea name="beschrijving" cols="70" rows="10"></textarea></td>
        </tr>
        <tr>
            <th align="left" valign="top">volg_nr</th>
            <td><input type="text" name="volg_nr" value="0"></td>
        </tr>
        <tr>
            <td><a href="index.php?page=edit&delete=ja&tabel=foto&id=1" onclick="javascript: return confirm('Weet je zeker dat je deze waarde wilt wissen?')"><input type="button" class="submit" name="wissen" value="wissen"></a></td>
            <td><input type='submit' class='submit' name='submit_edit' value='opslaan'></td>
        </tr>
    </table>
</form>