姜戈。向用户模型现有模型添加新属性外键：OperationalError

Question

我有之前创建的现有模型，我想将 ForeignKey 属性添加到用户模型，当我运行迁移命令时，出现以下错误（图像中的完整跟踪）： 模型：

class Patient(models.Model):
    number = models.IntegerField()
    last_name = models.CharField(max_length=30)
    first_name = models.CharField(max_length=30)
    middle_name = models.CharField(max_length=30)
    birthday = models.DateField(default=datetime.date.today)
    age = models.IntegerField(null=True)
    fromdate = models.DateField(default=datetime.date.today)
    appdate = models.DateField(default=datetime.date.today)
    district = models.ForeignKey(District, on_delete = models.CASCADE)
    address = models.TextField(default='')
    gender = models.BooleanField(default=True)
    occupation = models.ForeignKey(Occupation, on_delete = models.CASCADE)
    # it is extra field for patient to prevent from deleting them
    status = models.BooleanField(default=True)

    author = models.ForeignKey(
        User,
        on_delete=models.CASCADE,
    )

另外，在另一个项目中，我做了同样的动作，没有遇到任何困难。