protected function calculateAdditionalFiltersData(& $filters)
	{
		if (!empty($this->additional_filters_data)) {
			foreach ($this->additional_filters_data as $f => $src) {
				if (isset($src['query'])) {
					$filters[$f] = $this->query->pdo->query($src['query'])->fetchColumn();
				}
			}
		}
	}