Those checkboxes again

hi, I'm severely frustrated and perhaps you can help with what I have done wrong. The checkboxes I use to populate an intersection table work to add the records, and now I am trying to update them. It's almost there but producing some unexpected results when the form is submitted: the idea is that it displays the checkboxes as pre-selected if they're associated with the art_id in the intersection table. They're now appearing as all unselected. Any help is appreciated. <?php $query = ''; $result = 0; $art_id = $_POST['art_id']; print_r($_POST); if (isset($_POST['editrecordMedia'])){ if (!empty($_POST['media_types'])) { foreach($_POST['media_types'] as $type) { $query = "UPDATE media_art SET media_id='$type', art_id='$art_id'"; var_dump($query); mysql_query($query) or die(mysql_error()); } } else {echo "mediatypes is empty";} //Closes if (!empty($media_types))

    }//closes if (isset($_POST['editrecordMedia'])

//If editrecord hasn't been set, but selectcartoon has, get the cartoon's recordset //This is just to get the title for display purposes $query = "SELECT art_title FROM art WHERE art_id='$art_id'"; //end $media_query = "SELECT media.media_id, media.media_name, media_art.art_id FROM media LEFT JOIN media_art ON media_art.media_id=media.media_id AND media_art.art_id='$art_id'"; //These $art results are just to get the title for display purposes $art_result = mysql_query($query); $art_rows = mysql_fetch_assoc($art_result); //end $media_result = mysql_query($media_query); $checkbox_media = array (); while ($media_rows = mysql_fetch_assoc($media_result)){ $checkbox_media[] = "<input type='checkbox' name='media_types[]' value='{$media_rows['media_id']}' "; if ($media_rows['art_id'] === $art_id) { $checkbox_media[] .= "checked "; } $checkbox_media[] .= "/>{$media_rows['media_name']} "; } ?> <table align="center">

        <tr><th colspan="4">Main Menu</th></tr>
    <tr>
        <td><a href="addrecord.php">Add A Record</a></td>
        <td><a href="chooserecord.php">Edit A Record</a></td>
        <td><a href="deleterecord.php">Delete A Record</a></td>
    </tr>

</table> <form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post" name="editrecordMedia"> <input type="hidden" name="art_id" value="<?php echo $art_id ;?>"> Choose media related to <strong><?php echo $art_rows['art_title'];?></strong><br /><br /> Media: <?php echo join($checkbox_media); ?> <input type="submit" name="editrecordMedia" value="Update">

    </form>