php封装数据库

<?php
class Database {
    private $host = "localhost";
    private $db_name = "mydatabase";
    private $username = "root";
    private $password = "";
    public $conn;

    public function getConnection() {
        $this->conn = null;

        try {
            $this->conn = new PDO("mysql:host=" . $this->host . ";dbname=" . $this->db_name, $this->username, $this->password);
            $this->conn->exec("set names utf8");
        } catch(PDOException $exception) {
            echo "Connection error: " . $exception->getMessage();
        }

        return $this->conn;
    }
}

$db = new Database();
$conn = $db->getConnection();

$query = "SELECT * FROM users WHERE id = :id";
$stmt = $conn->prepare($query);
$stmt->bindParam(":id", $id);
$id = 1;
$stmt->execute();
$result = $stmt->fetch(PDO::FETCH_ASSOC);

echo json_encode($result);
?>