/**
  * @return OqlProjectionClause
  **/
 public static function groupBy($clause)
 {
     return OqlGroupByParser::create()->parse($clause);
 }
 private function groupByState()
 {
     if ($this->checkKeyword($this->tokenizer->peek(), 'group by')) {
         $this->tokenizer->next();
         $this->oqlObject->addGroupBy(OqlGroupByParser::create()->setTokenizer($this->tokenizer)->parse());
     }
     return self::ORDER_BY_STATE;
 }