How to rollback makemigrations in django?

Question

Django

Added a field to the model:

slug = models.SlugField(u'url', max_length=255, blank=True, null=True, unique=True)

didn't specify a default value, ran makemigrations.
Django created the migrations, but when you call migrate, it throws this error:

django.db.utils.IntegrityError: (1062, "Duplicate entry '' for key 'slug'")

Those. django is trying to create a unique field with the same value.
How can this last makemigrations be rolled back? Or maybe do some kind of test before makemigrations so that there are no such accidents?

Answer 1

Just delete this migration file if it hasn't already been applied. Correct and run makemigrations again.
Manage.py show migrations shows applied and unapplied migrations.
By specifying a number, you can rollback to a previous migration
manage.py migrate <model> <migration number>

Answer 2

Unknown command: 'show'. Did you mean show_urls?
Why is there no such command?