交易表中的用户余额

Question

我很想知道在交易表中监控用户余额的最佳方式，其中交易是存款或取款。

我目前的表结构是：

private $id;
private $user;
private $type; //credit or debit
private $identity; //deposit, transfer, withdraw
private $amount;
private $description;
private $scoredFee; //fixed charge
private $commission; //% charge
private $method; //cc, wallet etc.
private $status;

要计算出用户余额，我只需将所有贷方的总和减去所有借方的总和：

public function getUserBalance(User $userObject)
{
    $credits = $this->transactionRepository->createQueryBuilder('u')
        ->add('select','SUM(u.amount)')
        ->where('u.status = :status')
        ->andWhere('u.type = :type')
        ->andWhere('u.user = :userObject')
        ->setParameter('status' , 1)
        ->setParameter('type' , 1)
        ->setParameter('userObject' , $userObject)
        ->getQuery()
        ->getSingleScalarResult();

    $debits = $this->transactionRepository->createQueryBuilder('u')
        ->add('select','SUM(u.amount)')
        ->where('u.status = :status')
        ->andWhere('u.user = :userObject')
        ->andWhere('u.type = :type')
        ->setParameter('status' , 1)
        ->setParameter('userObject' , $userObject)
        ->setParameter('type' , 2)
        ->getQuery()
        ->getSingleScalarResult();

    $balance = $credits - $debits;

    if (null == $balance)
    {
        return 0;
    }

    return $balance;

}

我考虑的另一种方法是在用户表中设置一个固定的帐户余额，每次用户进行交易时都会计算出来。我唯一的保留是与此不同步的边缘情况。

有更好的方法吗？

Answer 1

您可以通过解码金额（我想是加法或减法）来简化仅一个查询，如下所示：

public function getUserBalance(User $userObject)
{
    $qb = $this->transactionRepository->createQueryBuilder('u');

    $qb ->add('select','SUM(CASE WHEN u.type = 1 then u.amount ELSE -u.amount END)')
        ->where('u.status = :status')
        ->andWhere($qb->expr()->in('u.type', array(1,2)))
        ->andWhere('u.user = :userObject')
        ->setParameter('status' , 1)
        ->setParameter('userObject' , $userObject);

    $balance = $qb
        ->getQuery()
        ->getSingleScalarResult();

    return $balance;

}

希望有帮助