Pimcore\Model\Document\Service\Dao::getTranslationSourceId PHP Method

    public function getTranslationSourceId(Document $document)
    {
        $sourceId = $this->db->fetchOne("SELECT sourceId FROM documents_translations WHERE id = ?", $document->getId());
        if (!$sourceId) {
            $sourceId = $document->getId();
        }
        return $sourceId;
    }