title: table has more than one primary key Django
body: <p>I have got error. For start when I create models, I make mistake and give pk for all <code>id</code> fields in models. Then I make this right and change for unique, but when I <code>makemigrations</code> I get error, I try to delete DB, try to change venv for new, but it do nothing with this error, I think I make mistake in code, but can't find it.</p>
  
  <p>models.py code:</p>
  
  <pre><code>class MainContact(models.Model):
      main_contact_id = models.IntegerField(null=True, unique=True)
  
  class Company(models.Model):
      company_id = models.IntegerField(null=True, unique=True)
      company_name = models.CharField(max_length=255, null=True)
  
  class Tags(models.Model):
      tags_id = models.IntegerField(null=True, unique=True)
      tags_name = models.CharField(max_length=255, null=True)
  
  class CustomFiledsValues(models.Model):
      custom_fields_values_value = models.CharField(max_length=255, null=True)
      custom_fields_values_enum = models.CharField(max_length=255, null=True)
      custom_fields_values_subtype = models.CharField(max_length=255, null=True)
  
  class CustomFields(models.Model):
      custom_fields_id = models.IntegerField(null=True, unique=True)
      custom_fields_name = models.CharField(max_length=255, null=True)
      custom_fields_values = models.ForeignKey(CustomFiledsValues, on_delete = models.CASCADE)
      custom_fields_is_system = models.BooleanField()
  
  class Contacts(models.Model):
      contact_id = models.IntegerField(null=True, unique=True)
  
  class Pipeline(models.Model):
      pipeline_id = models.IntegerField(null=True, unique=True)
  
  class Deal(models.Model):
      deal_id = models.IntegerField(null=True, unique=True)
      name = models.CharField(max_length=255, null=True)
      responsible_user_id = models.IntegerField(null=True)
      created_by = models.IntegerField(null=True)
      created_at = models.DateTimeField()
      updated_at = models.DateTimeField()
      account_id = models.IntegerField(null=True)
      is_deleted = models.BooleanField()
      main_contact = models.ForeignKey(MainContact, on_delete=models.CASCADE)
      group_id = models.IntegerField(null=True)
      company = models.ForeignKey(Company, on_delete=models.CASCADE)
      closed_at = models.DateTimeField()
      closest_task_at = models.DateTimeField()
      tags = models.ForeignKey(Tags, on_delete=models.CASCADE)
      custom_fields = models.ForeignKey(CustomFields, on_delete=models.CASCADE)
      contacts = models.ForeignKey(Contacts, on_delete=models.CASCADE)
      status_id = models.IntegerField(null=True)
      sale = models.DecimalField(max_digits=19, decimal_places=2)
      pipeline = models.ForeignKey(Pipeline, on_delete=models.CASCADE)
  </code></pre>
  
  <p>Traceback:</p>
  
  <pre><code>Traceback (most recent call last):
    File "manage.py", line 15, in &lt;module&gt;
      execute_from_command_line(sys.argv)
    File "/home/megagun/Projects/venvs/erpmodtest/lib/python3.5/site-packages/django/core/management/__init__.py", line 371, in execute_from_command_line
      utility.execute()
    File "/home/megagun/Projects/venvs/erpmodtest/lib/python3.5/site-packages/django/core/management/__init__.py", line 365, in execute
      self.fetch_command(subcommand).run_from_argv(self.argv)
    File "/home/megagun/Projects/venvs/erpmodtest/lib/python3.5/site-packages/django/core/management/base.py", line 288, in run_from_argv
      self.execute(*args, **cmd_options)
    File "/home/megagun/Projects/venvs/erpmodtest/lib/python3.5/site-packages/django/core/management/base.py", line 335, in execute
      output = self.handle(*args, **options)
    File "/home/megagun/Projects/venvs/erpmodtest/lib/python3.5/site-packages/django/core/management/commands/migrate.py", line 200, in handle
      fake_initial=fake_initial,
    File "/home/megagun/Projects/venvs/erpmodtest/lib/python3.5/site-packages/django/db/migrations/executor.py", line 117, in migrate
      state = self._migrate_all_forwards(state, plan, full_plan, fake=fake, fake_initial=fake_initial)
    File "/home/megagun/Projects/venvs/erpmodtest/lib/python3.5/site-packages/django/db/migrations/executor.py", line 147, in _migrate_all_forwards
      state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
    File "/home/megagun/Projects/venvs/erpmodtest/lib/python3.5/site-packages/django/db/migrations/executor.py", line 244, in apply_migration
      state = migration.apply(state, schema_editor)
    File "/home/megagun/Projects/venvs/erpmodtest/lib/python3.5/site-packages/django/db/migrations/migration.py", line 122, in apply
      operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
    File "/home/megagun/Projects/venvs/erpmodtest/lib/python3.5/site-packages/django/db/migrations/operations/models.py", line 92, in database_forwards
      schema_editor.create_model(model)
    File "/home/megagun/Projects/venvs/erpmodtest/lib/python3.5/site-packages/django/db/backends/base/schema.py", line 298, in create_model
      self.execute(sql, params or None)
    File "/home/megagun/Projects/venvs/erpmodtest/lib/python3.5/site-packages/django/db/backends/base/schema.py", line 117, in execute
      cursor.execute(sql, params)
    File "/home/megagun/Projects/venvs/erpmodtest/lib/python3.5/site-packages/django/db/backends/utils.py", line 100, in execute
      return super().execute(sql, params)
    File "/home/megagun/Projects/venvs/erpmodtest/lib/python3.5/site-packages/django/db/backends/utils.py", line 68, in execute
      return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
    File "/home/megagun/Projects/venvs/erpmodtest/lib/python3.5/site-packages/django/db/backends/utils.py", line 77, in _execute_with_wrappers
      return executor(sql, params, many, context)
    File "/home/megagun/Projects/venvs/erpmodtest/lib/python3.5/site-packages/django/db/backends/utils.py", line 85, in _execute
      return self.cursor.execute(sql, params)
    File "/home/megagun/Projects/venvs/erpmodtest/lib/python3.5/site-packages/django/db/utils.py", line 89, in __exit__
      raise dj_exc_value.with_traceback(traceback) from exc_value
    File "/home/megagun/Projects/venvs/erpmodtest/lib/python3.5/site-packages/django/db/backends/utils.py", line 83, in _execute
      return self.cursor.execute(sql)
    File "/home/megagun/Projects/venvs/erpmodtest/lib/python3.5/site-packages/django/db/backends/sqlite3/base.py", line 301, in execute
      return Database.Cursor.execute(self, query)
  django.db.utils.OperationalError: table "amocrmapi_deal" has more than one primary key
  </code></pre>