Django 查询在哪里

发布于 2024-11-06 08:10:38 字数 496 浏览 1 评论 0原文

如何使用 django 对象查询来做到这一点：

 SELECT * FROM test WHERE (test_id IN (SELECT test_id FROM test_subject_set)) AND (test_begin_time < '') AND (test_end_time > '')

模型：

class Test(models.Model):
    id = models.AutoField(primary_key=True)
    user = models.ForeignKey(User)
    groups = models.ManyToManyField(Group)


class TestSubjectSet(models.Model):
    id =  models.AutoField(primary_key=True)
    test = models.ForeignKey(Test)

原文

How to do this using django object query:

 SELECT * FROM test WHERE (test_id IN (SELECT test_id FROM test_subject_set)) AND (test_begin_time < '') AND (test_end_time > '')

The model:

class Test(models.Model):
    id = models.AutoField(primary_key=True)
    user = models.ForeignKey(User)
    groups = models.ManyToManyField(Group)


class TestSubjectSet(models.Model):
    id =  models.AutoField(primary_key=True)
    test = models.ForeignKey(Test)

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甜味拾荒者 2024-11-13 08:10:38

两个查询集是记录执行此操作的方法。无论如何，这将是一个数据库命中。

test_ids = Subject.objects.all()
result = Test.objects.filter(test_id__in=test_ids).filter([some other filtering])

Two querysets are documented way of doing this. It will be one database hit anyway.

test_ids = Subject.objects.all()
result = Test.objects.filter(test_id__in=test_ids).filter([some other filtering])

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疧_╮線 2024-11-13 08:10:38

泰莎博士差一点就明白了。

test_ids = list(TestSubjectSet.objects.all().values_list('test_id', flat=True))
result = Test.objects.filter(id__in=test_ids, test_begin_time__lt='', test_end_time__gt='')

Tyrsa 执行此操作的方式不会为您提供 TestSubjectSet 中的测试 ID 列表，而是为您提供 TestSubjectSet 查询集。

另外，我对 test_begin_time 和 test_end_time 字段感到困惑，因为您没有在模型中提及它们。

更新：在查询集上使用 list() ，因为根据 DrTyrsa 发布的链接，数据库“不能很好地优化嵌套查询集”。

DrTyrsa just about had it.

test_ids = list(TestSubjectSet.objects.all().values_list('test_id', flat=True))
result = Test.objects.filter(id__in=test_ids, test_begin_time__lt='', test_end_time__gt='')

The way Tyrsa was doing it would not give you a list of the Test ids from TestSubjectSet, but instead give you a TestSubjectSet queryset.

Also, I was confused by the test_begin_time and test_end_time fields, because you didn't mention them in your models.

Update: Used list() on the queryset, because, according to the link DrTyrsa posted, DBs "don't optimize nested querysets very well".

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