title: Target database is not up to date
body: <p>I'd like to make a migration for a Flask app. I am using Alembic.</p>
  <p>However, I receive the following error.</p>
  <pre class="lang-none prettyprint-override"><code>Target database is not up to date.
  </code></pre>
  <p>Online, I read that it has something to do with this.
  <a href="http://alembic.zzzcomputing.com/en/latest/cookbook.html#building-an-up-to-date-database-from-scratch" rel="noreferrer">http://alembic.zzzcomputing.com/en/latest/cookbook.html#building-an-up-to-date-database-from-scratch</a></p>
  <p>Unfortunately, I don't quite understand how to get the database up to date and where/how I should write the code given in the link.</p>