$result = @mysql_query ($query);
を変更します
と
$result = mysql_query ($query) or die(mysql_error());
エラーがないか確認してください。
編集:
oc.priceの後、prd.products_idの前にコンマがありません。クエリを次のように変更します:
$query = "SELECT us.users_id, us.users_first_name, us.users_surname, us.users_business,
ord.order_id, ord.users_id, ord.total, ord.order_date,
oc.oc_id, oc.order_id, oc.products_id, oc.quantity, oc.price/*here*/,/**/
prd.products_id, prd.products_name, prd.price
FROM users AS us, orders AS ord, order_contents AS oc, products AS prd
WHERE ord.order_id=$id
AND us.users_id = ord.users_id
AND ord.order_id = oc.order_id
AND oc.products_id = prd.products_id
";