如何在DJango中使用带注释的子查询的结果

Question

我有以下模型：

class CollegeResult(models.Model):
   id = models.IntegerField(primary_key=True)
   college_code = models.CharField(max_length=255, blank=True, null=True)
   college_name = models.CharField(max_length=255, blank=True, null=True)
   branch_name = models.CharField(max_length=255, blank=True, null=True)
   cutoff_type = models.CharField(max_length=255, blank=True, null=True)
   stage_mark = models.IntegerField(blank=True, null=True)
   stage_rank = models.IntegerField(blank=True, null=True)

我想从学院代码，分支名称的组中列出具有max（stage_mark）的行。

我尝试过的方法：

1. 原始查询，但是它容易受到SQL注入的攻击。<​​/ li>
2. query1 = CollegeResult.objects.filter(cutoff_type__in=quota) query2 = query1.values('college_code', 'branch_name') .annotate(stage_mark=Max('stage_mark'))
   但是我不知道如何使用query2结果来过滤query1结果。

3. query1 = CollegeResult.objects.filter(cutoff_type__in=quota) query2 = query1.values('college_code','branch_name') .annotate(stage_mark=Max('stage_mark')) q_statement = Q() for college in query2: q_statement |= (Q(college_code=college['college_code']) & Q(branch_name=college['branch_name']) & Q(stage_mark=college['stage_mark']) ) query3 = query1.filter(q_statement)

   这给 django.db.utils.OperationalError：SQL变量过多

我应该怎么做？