class DatabaseTestForm

class DatabaseTestForm extends FormBase {
  
  /**
   * {@inheritdoc}
   */
  public function getFormId() {
    return 'database_test_theme_tablesort';
  }
  
  /**
   * {@inheritdoc}
   */
  public function buildForm(array $form, FormStateInterface $form_state) {
    $header = [
      'username' => [
        'data' => t('Username'),
        'field' => 'u.name',
      ],
      'status' => [
        'data' => t('Status'),
        'field' => 'u.status',
      ],
    ];
    $query = Database::getConnection()->select('users_field_data', 'u');
    $query->condition('u.uid', 0, '<>');
    $query->condition('u.default_langcode', 1);
    $count_query = clone $query;
    $count_query->addExpression('COUNT([u].[uid])');
    $query = $query->extend(PagerSelectExtender::class)
      ->extend(TableSortExtender::class);
    $query->fields('u', [
      'uid',
    ])
      ->limit(50)
      ->orderByHeader($header)
      ->setCountQuery($count_query);
    $uids = $query->execute()
      ->fetchCol();
    $options = [];
    foreach (User::loadMultiple($uids) as $account) {
      $options[$account->id()] = [
        'title' => [
          'data' => [
            '#title' => $account->getAccountName(),
          ],
        ],
        'username' => $account->getAccountName(),
        'status' => $account->isActive() ? t('active') : t('blocked'),
      ];
    }
    $form['accounts'] = [
      '#type' => 'tableselect',
      '#header' => $header,
      '#options' => $options,
      '#empty' => t('No people available.'),
    ];
    return $form;
  }
  
  /**
   * {@inheritdoc}
   */
  public function submitForm(array &$form, FormStateInterface $form_state) {
  }

}