จะทำ preselect dropdownlist โดยส่งค่ามาจากอีกหน้า ต้องทำยังไงครับ

<?php
$id = $_POST['id'];

echo "<select name=\"ddl\">";
echo "<option value=\"0\">--SELECT--</option>";	
	$sql = "SELECT id ,name FROM tb_name ";
	$qr = mysql_query($sql) or die (mysql_error());
	while($fetch = mysql_fetch_assoc($qr)){
		if($fetch['id'] == $id){
			$sel = "selected";
		}else{
			$sel "";
		}
		echo "<option value=\"".$fetch['id']."\" ".$sel." >".$fetch['name']."</option>";
	}
	
echo "</select>";
?>