title: Django Column 'id' cannot be null
body: <p>I am having a weird problem with my mysql database and django.</p>
  
  <p>I created an app with a model imported from an existing database with inspectdb. It was working fine until yesterday I removed the django automatically created tables (django_<em>, auth_</em>, site_*). I did that because it was preventing my model to validate when I added my app in the installed apps.</p>
  
  <p>Now today I tried inserting a new record in my database and I get the following error :</p>
  
  <pre><code>Django Version:     1.3
  Exception Type:     IntegrityError
  Exception Value: (1048, "Column 'asset_id' cannot be null")
  </code></pre>
  
  <p>The field is a primary key and it's supposed to be auto_increment so I don't give a value to it when I create a new record.</p>
  
  <p>Can someone point me what's going on here ?</p>
  
  <p>EDIT : I partly figured out the problem : somehow all my auto_increment proprities were removed from my database. How did that happen ?</p>