Nette\Database\Table\Selection::alias PHP Method

    public function alias($tableChain, $alias)
    {
        $this->sqlBuilder->addAlias($tableChain, $alias);
        return $this;
    }

 /**
  * @param Selection $context
  * @param int $sectionId
  * @param string $via [optional]
  * @return Selection
  */
 public function filterSection(Selection $context, $sectionId, $via = '')
 {
     $context->alias($this->sectionTableName, 'alternate_section');
     $filterFactory = new Filter\Factory($this->sectionTableName);
     $nFilter = $filterFactory->createN($context);
     $nFilter->setup('id', $sectionId)->via("{$via}:page_has_section");
     $nFilter->setup('id', $sectionId, 'alternate_section')->via($via);
     return $nFilter->build();
 }