论学说中的无关联领域秩序

我有两个数据库表, orders 和 orderdetails subTotalAmount (计算字段)如下:

Order.php命令

private $subTotalAmount;

public function calculateSubTotalAmount(){

    $subtotal = 0;
    foreach ($this->getOrderDetails() as $detail) {
        $subtotal = $subtotal + $detail->getPrice();
    }
    $subtotal = $subtotal -$this->getDiscount();
    return $subtotal;
}

    public function getSubTotalAmount()
{
    $this->subTotalAmount = $this->calculateSubTotalAmount();
    return $this->subTotalAmount;
}

我希望能够按此字段排序,但鉴于此字段不相关,当我尝试时,会得到错误:

[语义错误]第0行,第135列,靠近“subTotalAmount”:错误: 小计金额

有没有可能按此字段订购?

我要在中实现的查询是:

public function searchAndSort($term, $sortAttribute, $sortOrder)
{
    $qb = $this->createQueryBuilder('po');
    $qb->andWhere('po.invoiceNumber LIKE :term or u.email LIKE :term')
        ->LeftJoin('po.orderedBy',  'u')
        ->setParameter('term', '%'.$term.'%')
        ->orderBy($sortAttribute, $sortOrder)
        ->getQuery()->getResult();
    return $qb;
}