title: CommandError: App 'books' has migrations. Only the sqlmigrate and sqlflush commands can be used when an app has migrations
body: <p>I am trying to learn about <code>python-django</code>.
  I want to make self app named books.</p>
  
  <p>When I ran this command</p>
  
  <pre><code>$ python manage.py sqlall books
  </code></pre>
  
  <p>Following error arises</p>
  
  <blockquote>
    <p>CommandError: App 'books' has migrations. Only the sqlmigrate and sqlflush commands can be used when an app has migrations.</p>
  </blockquote>
  
  <p>I did not understand why this error arise and what does it mean? Any help would be appreciated. Thanks</p>