title: sqlalchemy core with labels and joins postgres
body: <p>Using sqlalchemy expression language, I wish to select ids from 2 table. Hence I need to use labels. How to resolve this problem. I need ids and all other attribute values from the related tables. Code snippet is as follows:</p>
  
  <pre><code>s1 = select([rt_issues.c.id.label('rt_issue_id'),
               rt_issues,
               queues.c.id.label('q_id'),
               queues,
              ]).\
      where(rt_issues.c.id == issue_id).\
      select_from(rt_issues.
      outerjoin(queues,
                rt_issues.c.queue_id == queues.c.id))
  rs1 = conn.execute(s1)
  </code></pre>
  
  <p>Error log:  </p>
  
  <blockquote>
    <p>"try 'use_labels' option on select statement." % key)
    InvalidRequestError: Ambiguous column name 'id' in result set! try
    'use_labels' option on select statement.</p>
  </blockquote>