php mysql查询的问题

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

try {
    $conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $stmt = $conn->prepare("SELECT id, name FROM myTable");
    $stmt->execute();

    $result = $stmt->setFetchMode(PDO::FETCH_ASSOC);
    $row = $stmt->fetch();
    echo "id: " . $row['id'] . ", name: " . $row['name'];
} catch(PDOException $e) {
    echo "Error: " . $e->getMessage();
}

$conn = null;
?>