加密算法：对称加密算法+非对称算法
对称加密算法：加密密匙⇔解密密匙，加密用加密算法，解密用加密算法的逆算法。
非对称算法：公开密匙+私有密匙。私有密匙为自己持有（密匙持有者），公开密匙为与自己通信的人持有。密文经过私有密匙加密，只能公开密匙解密。相反，密文经过公开密匙加密，只能私有密匙解密。
椭圆曲线加密算法：使用数学中更抽象的椭圆曲线进行更安全的加密。
Note：在代数几何中，不严格的说，椭圆曲线为$y^{2}=f(x)$的解，其中$f(x)$为某个域$K$上的三次多项式。
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I have a Django model that used to look like this:class Car(models.Model): manufacturer_id = models.IntegerField()There is another model called Manufacturer that the id field refers to. However, I realized that it would be useful to use Django's built-in foreign key functionality, so I changed the model to this:class Car(models.Model): manufacturer = models.ForeignKey(Manufacturer)This change appears to work fine immediately, queries work without errors, but when I try to run migrations, Django outputs the following:- Remove field manufacturer_id from car - Add field manufacturer to carDoing this migration would clear all the existing relationships in the database, so I don't want to do that. I don't really want any migrations at all, since queries like Car.objects.get(manufacturer__name="Toyota") work fine. I would like a proper database foreign key constraint, but it's not a high priority.So my question is this: Is there a way to make a migration or something else that allows me to convert an existing field to a foreign key? I cannot use --fake since I need to reliably work across dev, prod, and my coworkers' computers.内容来源于 Stack Overflow, 遵循 CCBY-SA 4.0 许可协议进行翻译与使用。原文链接：Django change an existing field to foreign key
