code: protected function getCombinationsFromDatabase()
      {
          $groups = $this->getUserGroups();
          if (!$groups) {
              return null;
          }
  
          $statement = $this->connection->createQueryBuilder()
              ->select('*')
              ->from('tl_metamodel_dca_combine')
              ->where(strtolower(TL_MODE) . '_group IN (:groups)')
              ->orderBy('pid')
              ->addOrderBy('sorting', 'ASC')
              ->setParameter('groups', $groups)
              ->execute();
  
          return $statement->fetchAll(\PDO::FETCH_OBJ);
      }
docs: Retrieve the palette combinations from the database.
  
  @return array|\stdClass[]