<?php
declare(strict_types=1);
$db = new PDO('sqlite::memory:');
$db->exec('CREATE TABLE packet (id TEXT, name TEXT)');
$insert = $db->prepare('INSERT INTO packet VALUES (?, ?)');
$insert->execute(['p4', 'Peas & beans']);
$document = new DOMDocument('1.0', 'UTF-8');
$root = $document->appendChild($document->createElement('exchange'));
foreach ($db->query('SELECT id, name FROM packet ORDER BY id') as $row) {
    $packet = $root->appendChild($document->createElement('packet'));
    $packet->setAttribute('id', $row['id']);
    $packet->appendChild($document->createTextNode($row['name']));
}
echo $document->saveXML($document->documentElement), PHP_EOL;