Django：多个表模型查询

Question

我已经在Q对象和Django Orm上尝试过，但无法生成查询。

class Status(models.Model):
    id = models.AutoField(primary_key=True)
    name = models.AutoField(null=True, max_length=100)
    
    def __str__(self):
        return self.name
        
class Billing(models.Model):
    id = models.AutoField(primary_key=True)
    name = models.AutoField(null=True, max_length=1000)
    sr_number = models.AutoField(null=True, max_length=100)
    
    def __str__(self):
        return self.name
        
class BillingInfo(models.Model):
    id = models.AutoField(primary_key=True)
    billings = models.ForeignKey(Billing, null=True, on_delete=models.SET_NULL)
    net_amount = models.AutoField(null=True, max_length=100)
    company = models.AutoField(null=True, max_length=100)
    
    def __str__(self):
        return self.company
        
class BillingOutput(models.Model):
    id = models.AutoField(primary_key=True)
    billing_infos = models.ForeignKey(BillingInfo, null=True, on_delete=models.SET_NULL)
    lbl_name = models.AutoField(null=True, max_length=100)
    lbl_qty = models.AutoField(null=True, max_length=100)
    status = models.ForeignKey(Status, null=True, on_delete=models.SET_NULL)
    
    def __str__(self):
        return self.lbl_name

我需要以下RAW SQL查询的等效orm查询：

select bio.* from billing bil
    inner join billing_infos bi on bil.id = bi.billings_id
    inner join billing_output bio on bi.id = bio.billing_infos_id
    where bo.status_id = 1
    order by bio.id desc;

有人可以帮我解决这个问题吗？

Answer 1

您可以使用 .select_redated（… ）＆nbsp; [django-doc]检索相关billing_infos和billing Billing_infos：

BillingOutput.objects.select_related(
    'billing_infos__billing'
).filter(status_id=1, billing_infos__billing__isnull=False).order_by('-id')

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注意：django默认将添加 autofield ＆nbsp; ^[django-doc] 作为priendar_key = primary_key = true使用名称ID如果自己未指定主键，则无需明确声明主键。

Answer 2

实际上，您可以这样做：

qry1 = "select bio.* from billing bil
            inner join billing_infos bi on bil.id = bi.billings_id
            inner join billing_output bio on bi.id = bio.billing_infos_id
            where bo.status_id = 1
            order by bio.id desc;" 
bio = Billing.objects.raw(qry1 , [user_id])