Scripts php/mysql

Bonjour,
mon 1er page:
-----------------------

<form action='bruan.php' method='post' name='form'>
code: <input type='text' name='co' value='' size='10'><br>
<br>
code postal: <input type='text' name='cop' value='' size='10'><br>
<br>
ville: <input type='text' name='vi' value='' size='20'><br><br>
<input type='submit' name='valider' value='insert'>
</form>

mon 2eme page:
------------------------

<?php
extract ($_POST,EXTR_OVERWRITE);

$id=mysql_connect("localhost","root","") or die ("serveur introuvable!!!");
$db=mysql_select_db("immobilier") or die ("base introuvable!!!");
$res=mysql_query("insert into biens ('code','code_postal','ville') values ($co,$cop,$vi)");
echo"merci de votre attention";
mysql_close ($id);
?>

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la mise a jour du bd ca marche pas pourquoi ,aidez moi svp,merciiiiiiiiiiiiiiiiiiiiii