title: How to solve "table "auth_permission" already exists" error when the database is shared among two Django projects
body: <p>in <a href="https://stackoverflow.com/questions/39774580/how-to-make-two-django-projects-share-the-same-database/39781404?noredirect=1#comment66877315_39781404">this</a> question I learned how to make two Django projects use the same database.
    I have:</p>
  
  <pre><code>projects
    project_1
      settings.py
      ...
    project_2
      settings.py
      ...
  </code></pre>
  
  <p>and</p>
  
  <pre><code># project_1/settings.py
  
  DATABASES = {
      'default': {
          'ENGINE': 'django.db.backends.sqlite3',
          'NAME': os.path.join(PROJECT_ROOT, 'development.db'),
      },
  }
  
  
  # project_2/settings.py
  
  DATABASES = {
      'default': {
          'ENGINE': 'django.db.backends.sqlite3',
          'NAME': os.path.join(
              os.path.dirname(os.path.dirname(PROJECT_ROOT)),
              'project_1',
              'development.db'
          ),
      },
  }
  </code></pre>
  
  <p>In <code>project_2/</code>, when I run:</p>
  
  <pre><code>python manage.py syncdb
  </code></pre>
  
  <p>I get:</p>
  
  <pre><code>django.db.utils.OperationalError: table "auth_permission" already exists
  </code></pre>
  
  <p>I guess this happens because python fails in trying to add <code>project_2</code> tables that already exists in the shared db.</p>
  
  <p>How can I add to the shared db only those <code>project_2</code> tables not already existing in the common database?</p>
  
  <p><strong>EDIT:</strong>
  After telling project_2/ to use project_1/ db, I run the <code>syncdb</code> and get the existing table error. I do  not have a migration file.
   Shall I run a different command before syncing?</p>