Help with update

[rakuci]

Hi guys,
I really need hel on this
I have a multiple select box and multiple hidden field
<select name="media[]" class="veld" style="width:50mm" onChange="document.media.submit()">
<?
$sql_m = "SELECT m_id,m_naam FROM media";
$result_m = mysql_query($sql_m);

while ($row_m = mysql_fetch_array($result_m)) {
$selected = "";
if ($row_m["m_id"] == $media_id) {
$selected = "SELECTED";
}
?>
<option <?=$selected?> value='<?=$row_m["m_id"]?>'>
<?=$row_m["m_naam"]?>
</option>
<?
}
?>
<input type="hidden" name="jm_id[]" value="<?=$jm_id?>">
?>
</select>

I need help that when a form is send how to update the query in db
$sql = "UPDATE journalist_media SET ";
$sql = $sql . "jm_jFK = '" . $_POST['j_id'] . "', ";
$sql = $sql . "jm_mFK = '".$media[]."' ";
$sql = $sql . "WHERE jm_id ='" .$jm_id[] . "'";

$result = mysql_query($sql)or die(mysql_error());

Here is where I get stucked bij WHERE
I try with
foreach($media as $key=>$val){
echo $val;
}

[peppeto]

I think this can do
foreach ($media as $key => $value){

 $sql = "UPDATE journalist_media SET ";
             $sql = $sql . "jm_jFK = '" . $_POST['j_id'] . "', "; 
 $sql = $sql . "jm_mFK       = '".$value."' ";
             $sql = $sql . "WHERE jm_id  ='" .$key . "'";

$result = mysql_query($sql)or die(mysql_error());
}