ทําไมถึงขึ้นแบบนี้ Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result resource in C:\AppServ\www\keng\test1.php on line 13 not

<?php
include("connect.php");
$str = "select * form topchart where = id";
$query = mysql_query($str);
$result = mysql_fetch_array($query);
if($result){
    		
echo $result["id"];
echo $result["song"];
}
else
{
echo "not";	
}

?>

<?php
$host = "localhost";
$username = "root";
$password = "1234";
$dbname = "topchart";

$connect = mysql_connect($host,$username,$password,$dbname) or die ("ไม่สามารถติดต่อฐาข้อมูลได้");
mysql_query("SET NAMES UTF8");

mysql_select_db("$dbname");
?>