src/Db/Database.php
public function getQueryBuilder() {
        if (!isset($this->_queryBuilder)) {
            /** @var QueryBuilderInterface $queryBuilder */
            $queryBuilder = $this->createComponent(QueryBuilderInterface::class);
            $this->_queryBuilder = $queryBuilder;
        }
        return $this->_queryBuilder;
    }
public function getQueryBuilder() {
        if (!isset($this->_queryBuilder)) {
            /** @var QueryBuilderInterface $queryBuilder */
            $queryBuilder = $this->createComponent(QueryBuilderInterface::class);
            $this->_queryBuilder = $queryBuilder;
        }
        return $this->_queryBuilder;
    }
Get query builder
@return QueryBuilderInterface