<?php
require 'DB.php';

$conn = DB::connect("dsn");
if (DB::isError($conn))
  die("connection failed: ".$conn->getMessage());

$result = $conn->query("SELECT ... ");
if (DB::isError($result))
  die("query failed: ".$result->getMessage());

while ($row = $result->fetchRow(DB_FETCHMODE_ASSOC)) {
  echo " $row[id] ... ";
}