$table2dump = 'table_name';
$file_content = '';
 
$sql = "SHOW COLUMNS FROM " . $table2dump ;
$res = mysql_query($sql);
while ($row = mysql_fetch_assoc($res)) 
{
	$file_content .= $row['Field'].',';
}
$file_content = substr($file_content, 0, -1)."\n";
 
$sql = "SELECT * FROM " . $table2dump ;
$res = mysql_query($sql);
while ($row = mysql_fetch_assoc($res)) 
{
	$file_content  .= implode(',', $row)."\n";
}
header("Content-type: application/vnd.ms-excel");
header("Content-disposition: csv; filename=" . date("Y-m-d") . "_" . $table2dump . ".csv; size=".strlen($file_content));
echo $file_content;
exit;