Excel export php

The below code can export data from database into excel sheet using php:

<?php
$filename ='excelreport.xls';

mysql_connect("localhost", "root", "") or die(mysql_error());
mysql_select_db("test");
$res = mysql_query("select id, country from countries");

$contents = '';

while($row = mysql_fetch_assoc($res))
{
$contents .= $row['id']."\t".$row['country']."\n";       
}

header('Content-type: application/ms-excel');
header('Content-Disposition: attachment; filename='.$filename);

header('Content-Transfer-Encoding: binary');
header('Expires: 0');
header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
header('Pragma: public');

echo $contents;
?>