Nextras\Orm\Mapper\Dbal\DbalMapper::builder PHP Method

    public function builder()
    {
        $tableName = $this->getTableName();
        $builder = new QueryBuilder($this->connection->getDriver());
        $builder->from("[{$tableName}]", QueryBuilderHelper::getAlias($tableName));
        return $builder;
    }

 protected function fetchByTwoPassStrategy(QueryBuilder $builder, array $values, IEntityPreloadContainer $preloadContainer = NULL)
 {
     $builder = clone $builder;
     $targetPrimaryKey = $this->targetMapper->getStorageReflection()->getStoragePrimaryKey();
     $isComposite = count($targetPrimaryKey) !== 1;
     foreach (array_unique(array_merge($targetPrimaryKey, [$this->joinStorageKey])) as $key) {
         $builder->addSelect("[{$key}]");
     }
     $sqls = $args = [];
     foreach ($values as $primaryValue) {
         $builderPart = clone $builder;
         $builderPart->andWhere("%column = %any", $this->joinStorageKey, $primaryValue);
         $sqls[] = $builderPart->getQuerySQL();
         $args = array_merge($args, $builderPart->getQueryParameters());
     }
     $query = '(' . implode(') UNION ALL (', $sqls) . ')';
     $result = $this->connection->queryArgs($query, $args);
     $map = $ids = [];
     if ($isComposite) {
         foreach ($result as $row) {
             $id = [];
             foreach ($targetPrimaryKey as $key) {
                 $id[] = $row->{$key};
             }
             $ids[] = $id;
             $map[$row->{$this->joinStorageKey}][] = implode(',', $id);
         }
     } else {
         $targetPrimaryKey = $targetPrimaryKey[0];
         foreach ($result as $row) {
             $ids[] = $row->{$targetPrimaryKey};
             $map[$row->{$this->joinStorageKey}][] = $row->{$targetPrimaryKey};
         }
     }
     if (count($ids) === 0) {
         return new EntityIterator([], $preloadContainer);
     }
     if ($isComposite) {
         $builder = $this->targetMapper->builder();
         $builder->andWhere('%column[] IN %any', $targetPrimaryKey, $ids);
         $entitiesResult = [];
         $collection = $this->targetMapper->toCollection($builder);
         foreach ($collection as $entity) {
             $entitiesResult[implode(',', $entity->getValue('id'))] = $entity;
         }
     } else {
         $entitiesResult = $this->targetRepository->findBy([$targetPrimaryKey => $ids])->fetchPairs($targetPrimaryKey, NULL);
     }
     $entities = [];
     foreach ($map as $joiningStorageKey => $primaryValues) {
         foreach ($primaryValues as $primaryValue) {
             $entity = $entitiesResult[$primaryValue];
             $entities[$entity->getRawValue($this->metadata->relationship->property)][] = $entity;
         }
     }
     return new EntityIterator($entities, $preloadContainer);
 }