Python 使用Distinct-over-Django-manytomy关系从原始SQL进行Django查询
models.pyPython 使用Distinct-over-Django-manytomy关系从原始SQL进行Django查询,python,sql,django,distinct,Python,Sql,Django,Distinct,models.py class FlagsModel(models.Model): name = models.CharField(max_length=64, verbose_name='Flag') class ColorsModel(models.Model): name = models.CharField(max_length=64, verbose_name='Color') class RelationModel(models.Model): flag
class FlagsModel(models.Model):
name = models.CharField(max_length=64, verbose_name='Flag')
class ColorsModel(models.Model):
name = models.CharField(max_length=64, verbose_name='Color')
class RelationModel(models.Model):
flag = models.ForeignKey(FlagsModel, null=True, on_delete=models.SET_NULL)
color = models.ForeignKey(ColorsModel, null=True, on_delete=models.SET_NULL)
SQL表:
FlagsModel
+----+--------------+
| id | name |
+----+--------------+
| 1 | brazil |
| 2 | canada |
| 3 | china |
| 4 | portugal |
+----+--------------+
ColorsModel
+----+--------------+
| id | name |
+----+--------------+
| 1 | red |
| 2 | yellow |
| 3 | green |
+----+--------------+
RelationModel
+----+---------+----------+
| id | flag_id | color_id |
+----+---------+----------+
| 1 | 1 | 3 |
| 2 | 1 | 2 |
| 4 | 2 | 1 |
| 5 | 3 | 1 |
| 6 | 3 | 2 |
| 7 | 4 | 1 |
| 8 | 4 | 2 |
| 9 | 4 | 3 |
+----+---------+----------+
我现在正在寻找一个查询,它选择每个包含颜色“黄色”和“红色”的标志
在原始SQL中,我可以执行以下操作:
SELECT DISTINCT a1.flag_id from relationmodel a1, relationmodel a2 where a1.color_id=2 AND a2.color_id=1
但我还没有找到一个在django有效的解决方案
有什么想法吗?您可以使用以下方法进行筛选:
FlagModel.objects.filter(
relationmodel__color_id=1
).filter(
relationmodel__color_id=2
)
因此,对于给定的示例数据,它将返回中国和葡萄牙的标志。我不知道如何在Django中创建交叉连接(这就是您在sql中所做的…)
SELECT flagmodel.*
FROM flag
INNER JOIN relationmodel r1 ON r1.flag_id = flag.id
INNER JOIN relationmodel r2 ON r2.flag_id = flag.id
WHERE r1.flag_id = 1 AND r2.flag_id = 2