Django ForeignKey null = true

from django.db import models

class Story(models.Model):
    id = models.IntegerField(primary_key=True)
    news_type = models.CharField(max_length=255,null=True)
    category_id = models.CharField(max_length=255,null=True)
    title = models.CharField(max_length=255,null=True)
    created = models.DateTimeField(null=True)
    author = models.CharField(max_length=255, null=True)
    author_title = models.CharField(max_length=255, null=True)
    image_caption = models.TextField(null=True)
    image_credit = models.CharField(max_length=255,null=True)
    image_full_url = models.CharField(max_length=255,null=True)
    body = models.TextField(null=True)
    summary = models.TextField(null=True)
    video_id = models.CharField(max_length=255,null=True)
    external_url = models.CharField(max_length=255,null=True)
    order = models.IntegerField(null=True)

class StoryFactBox(models.Model):
    story = models.ForeignKey('Story', null = True)
    body = models.TextField()

class StoryKeyword(models.Model):
    story = models.ForeignKey('Story', null = True)
    keyword = models.CharField(max_length=255)

      

        
        
        
      

    

What schema changes are taking place models.ForeignKey('Story', null = True)

?

I read from the docs:

I want to use remove () and clear () and that is part of the documentation.

To prevent database inconsistency, this method only exists for ForeignKey objects where null = True. If the associated field cannot be set to None (NULL), then the object cannot be removed from the relationship without being added to another. In the above example, removing e from b.entry_set () is equivalent to doing e.blog = None, but because the ForeignKey blog does not have a null = True value, this is not correct.