title: SQLAlchemy: Column Shows up on Base.metadata.tables, but not inside the actual PostgreSQL table
body: <p>In my models, I have a base Interactions table that I inherit in my Comments and Likes table. The Likes has a foreign key relationship to my Comments table like so:</p>
  <pre class="lang-py prettyprint-override"><code>comment_id = psql.Column(
          psql.Integer,
          psql.ForeignKey('comments._id'),
          nullable=True
      )
  </code></pre>
  <p>When I try to create a like and supply values, SQLAlchemy cannot find the column and we end up with this error:</p>
  <pre><code>sqlalchemy.exc.ProgrammingError: (psycopg2.errors.UndefinedColumn) column &quot;comment_id&quot; of relation &quot;likes&quot; does not exist
  Jan  6 03:21:04: LINE 1: INSERT INTO likes (_id, comment_id, post_id) VALUES ('antor'...
  Jan  6 03:21:04:                                 ^
  Jan  6 03:21:04: [SQL: INSERT INTO likes (_id, comment_id, post_id) VALUES (%(_id)s, %(comment_id)s, %(post_id)s)]
  Jan  6 03:21:04: [parameters: {'_id': 'antor', 'comment_id': None, 'post_id': None}]
  Jan  6 03:21:04: (Background on this error at: http://sqlalche.me/e/13/f405)
  </code></pre>
  <p>...but when I look in my metadata and see the tables, I can see that the column is being made (the following is from Base.metadata.tables):</p>
  <p>'likes': Table('likes', MetaData(bind=None), Column('_id', String(length=64), ForeignKey('interactions.uid'), table=, primary_key=True, nullable=False), <strong>Column('comment_id', Integer(), ForeignKey('comments._id')</strong>, table=&lt;likes&gt;)</p>
  <p>However, when I check on for the column in the Likes table through postgreSQL commands, the column comment_id is not there.</p>
  <p>Not sure where I made an error on this one since the column shows up in SQLAlchemy but not the actual DB.</p>
  <p>So far, I've read through some other SQLAlchemy resources, namely this one on Mapping Class Inheritance Hierarchies, but I'm not sure that this is the issue since it looks like SQLAlchemy is trying to add the values into the right table:
  <a href="https://docs.sqlalchemy.org/en/14/orm/inheritance.html" rel="nofollow noreferrer">https://docs.sqlalchemy.org/en/14/orm/inheritance.html</a></p>