class Thread

class Thread extends SortPluginBase {
  public function query() {
    $this->ensureMyTable();
    // See \Drupal\comment\CommentStorage::loadThread() for an explanation of
    // the thinking behind this sort.
    if ($this->options['order'] == 'DESC') {
      $this->query
        ->addOrderBy($this->tableAlias, $this->realField, $this->options['order']);
    }
    else {
      $alias = $this->tableAlias . '_' . $this->realField . 'asc';
      // @todo is this secure?
      $this->query
        ->addOrderBy(NULL, "SUBSTRING({$this->tableAlias}.{$this->realField}, 1, (LENGTH({$this->tableAlias}.{$this->realField}) - 1))", $this->options['order'], $alias);
    }
  }

}