Symfony2原则查询生成器作为FROM子句中的子查询

我使用查询生成器得到了一个查询，该查询被分配给$qb变量。它在PHP和DB中都能很好地工作。现在，我正试图将该查询用作子查询，如下所示：

    $subQuery = $qb->getQuery()->getSql();
    $query = 'select res.some_name
              from ('.$subQuery.') as res';

但我得到了以下例外：

Caused by Doctrine'DBAL'Driver'PDOException: SQLSTATE[HY000]: General error: 1 no such column: res.some_name

由于Doctrine已经将$qb转换为类似于Doctrine转换原始SQL查询的内容。例如，有一个叫做AS legalenty_name的东西，但它显示的是AS名称1:

select res.some_name from (SELECT o0_.id AS id0, o0_.name AS name1, b1_.id AS id2, b1_.display AS display3, m2_.id AS id4, m2_.total AS total5 FROM Invoice i3_ INNER JOIN CodeableItem c4_ ON i3_.id = c4_.id INNER JOIN MonetaryItem m2_ ON i3_.id = m2_.id AND (1=1) INNER JOIN LineItem l5_ ON c4_.id = l5_.codeableItem_id LEFT JOIN MonetaryItem m6_ ON l5_.id = m6_.id AND (1=1) LEFT JOIN PresetLineItem p7_ ON c4_.id = p7_.codeableItem_id LEFT JOIN MonetaryItem m8_ ON p7_.id = m8_.id AND (1=1) INNER JOIN OrgUnit o0_ ON c4_.legalentity_id = o0_.id AND (1=1) INNER JOIN monetaryitem_listitem m9_ ON m2_.id = m9_.monetaryitem_id INNER JOIN BWListItem b1_ ON b1_.id = m9_.bwlistitem_id AND (1=1) INNER JOIN BWList b10_ ON b1_.bwlist_id = b10_.id AND (1=1) WHERE b10_.type = 'Vendor' GROUP BY c4_.legalentity_id, b1_.active, b1_.attributes, b1_.display, b1_.created, b1_.updated, b1_.lft, b1_.lvl, b1_.rgt, b1_.root, b1_.id, b1_.orgunit_id, b1_.bwlist_id, b1_.parent_id, b1_.rootou_id, m2_.created, m2_.updated, m2_.subtotal, m2_.total, m2_.description, m2_.id, c4_.number, c4_.externalId, c4_.status, c4_.overriddenDuringApproval, i3_.invoiceDate, i3_.dueDate, i3_.poNumber, m2_.rootou_id, c4_.image_id, c4_.legalentity_id, c4_.creator, c4_.owner_id ORDER BY o0_.name ASC, b1_.display ASC) as res

我的问题是：如何使用$subQuery中的原始SQL？任何帮助都是非常有益的。干杯