为什么PHP PDO不从我的数据库中提取任何东西(更确切地说，是UserPassword列)

<?php
$dsn = 'mysql:host=localhost;dbname=testdb;charset=utf8mb4';
$user = 'username';
$password = 'password';

try {
    $pdo = new PDO($dsn, $user, $password);
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    $userId = 1;
    $sql = "SELECT UserPassword FROM users WHERE id = :id";
    $stmt = $pdo->prepare($sql);
    $stmt->bindParam(':id', $userId, PDO::PARAM_INT);
    $stmt->execute();
    $result = $stmt->fetch(PDO::FETCH_ASSOC);

    if ($result) {
        echo "UserPassword: " . $result['UserPassword'];
    } else {
        echo "No data found for user ID: " . $userId;
    }
} catch (PDOException $e) {
    echo "Connection failed: " . $e->getMessage();
}
?>