如何使用PHP8中的Constructor Property Promotion来优化数据库查询操作？

class User
{
    public function __construct(
        private string $username, 
        private string $email
    ) {
        // 构造函数内部可以直接使用$username和$email，无需手动赋值
    }
}

class Database
{
    private PDO $pdo;
    
    public function __construct(string $host, string $username, string $passWord, string $database)
    {
        $this->pdo = new PDO("Mysql:host=$host;dbname=$database", $username, $password);
        $this->pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    }
    
    public function query(string $sql, array $params = []): PDOStatement
    {
        $stmt = $this->pdo->prepare($sql);
        $stmt->execute($params);
        
        return $stmt;
    }
}

+----+----------+--------------------+
| id | username | email              |
+----+----------+--------------------+
| 1  | user1    | user1@example.com  |
| 2  | user2    | user2@example.com  |
| 3  | user3    | user3@example.com  |
+----+----------+--------------------+

class User
{
    public function __construct(
        private int $id,
        private string $username,
        private string $email,
        private Database $database
    ) {}
    
    public static function find(int $id): User
    {
        $database = new Database('localhost', 'username', 'password', 'database');
    
        $stmt = $database->query('SELECT * FROM users WHERE id = :id', [':id' => $id]);
        
        return new self($stmt->fetch(PDO::FETCH_ASSOC), $database);
    }
    
    public function getUsername(): string
    {
        return $this->username;
    }
    
    public function getEmail(): string
    {
        return $this->email;
    }
}

$user = User::find(1);

if ($user) {
    echo $user->getUsername();  // 输出：user1
    echo $user->getEmail();     // 输出：user1@example.com
}