Mysql vers excel via php

Bonjour,
<?php

header("Content-type: application/vnd.ms-excel");
header("Content-Disposition: attachment; filename=nom_fichier.xls");


// selectionner la base de données

mysql_select_db($database_conn, $conn);
$sql = "SELECT * FROM client";
$sql = mysql_db_query($database_conn,$sql);

$tbl= " <table border='0' cellpadding='0' cellspacing='0'>
<tr bgcolor='#CCCCCC' height='40px'>
<td>nom</td>
<td>prenom</td>
<td>email</td>
</tr>";
while ($data = mysql_fetch_array($sql))
{
$tbl = $tbl . "<tr>";
$tbl = $tbl . "<td>" . $data[nom'] . "</td>";
$tbl = $tbl . "<td>" . $data['prenom'] . "</td>";
$tbl = $tbl . "<td>" . $data['email'] . "</td>";
$tbl = $tbl . "</tr>";
}
$tbl = $tbl . "</table>";

print $tbl ;
?>