public function getById($id)
    {
        $res = $this->conn->query("SELECT * FROM {$this->tbl} WHERE id = $id");
        if ($res->num_rows > 0) {
            $user = $res->fetch_assoc();
            return $user;
        }
        return false;
    }

    public function update($data)
    {
        $user = $this->getById($data['user_id']);
        if ($user['username'] == $data['username']) {
            $username = $data['username'];
            $data['username'] = false;
        } else {
            $username = $data['username'];
        }
        if ($data['password'] == null) {
            $password = $data['password2'];
            $data['password'] = false;
        } else {
            $password = md5($data['password']);
        }
        $validasi = $this->_validasi($data);
        if ($validasi == []) {
            $res = $this->conn->query("UPDATE {$this->tbl} SET nama='{$data['nama']}',username='{$username}',password='{$password}',email='{$data['email']}' WHERE id={$data['user_id']}");
            $this->conn->close();
            return $res;
        } else {
            return $validasi;
        }
    }

    public function delete($id)
    {
        $this->conn->query("DELETE FROM {$this->tbl} WHERE id = {$id}");
        if ($this->conn->affected_rows == 1) {
            return true;
        }
        return false;
    }