title: ALTER COLUMN in sqlite
body: <p>How do I alter column in sqlite?
  This is in <code>Postgresql</code></p>
  
  <pre><code>ALTER TABLE books_book ALTER COLUMN publication_date DROP NOT NULL;
  </code></pre>
  
  <p>I believe there is no ALTER COLUMN in sqlite at all, only ALTER TABLE is supported.</p>
  
  <p>Any idea? Thanks!</p>