php编写数据库类源码

class Database {
    private $host = "localhost";
    private $username = "root";
    private $password = "";
    private $dbname = "mydatabase";

    public function connect() {
        $conn = new mysqli($this->host, $this->username, $this->password, $this->dbname);
        if ($conn->connect_error) {
            die("连接失败: " . $conn->connect_error);
        }
        return $conn;
    }

    public function query($conn, $sql) {
        $result = $conn->query($sql);
        if ($result === false) {
            die("查询失败: " . $conn->error);
        }
        return $result;
    }

    public function close($conn) {
        $conn->close();
    }
}