Question

我有三种型号：

class Customer(models.Model):
    name = models.CharField(max_length=100)

class Transaction(models.Model):
    debited_customer = models.ForeignKey(Customer, null=True, blank=True)
    credited_customer = models.ForeignKey(Customer, null=True, blank=True)
    amount_equ = models.BigIntegerField(null=True, blank=True)

class Account(models.Model):
    customer = models.ForeignKey(Customer)

所有表名都是'pr_'+小写型号名称。有些客户没有账号。我想从所有交易中加上'amount_equ'，其中debited_customer或credited_customer是有帐户的客户。我可以使用原始SQL查询来实现这一点：

SELECT SUM(tt.amount_equ)
FROM (SELECT DISTINCT t.id, amount_equ
    FROM pr_transaction t INNER JOIN
    (SELECT DISTINCT c.id
        FROM pr_customer c INNER JOIN pr_account a ON c.id=a.customer_id) cc
    ON t.debited_customer_id=cc.id OR t.credited_customer_id=cc.id) tt

没有原始sql可以做同样的事情吗？如何？我试过了

Transaction.objects.filter(Q(credited_customer__account__isnull = False) | Q(debited_customer__account__isnull = False)).values('id').distinct()

并且它似乎提供了正确的交易集，但我不知道如何获得总和，我尝试.aggregate(Sum('amount_equ'))但在这种情况下它采用不同的'amount_equ'而不是不同的pk，结果变为错

django ORM查询三种型号

0 个答案: