title: What is the way to select a hard-coded value in a query?
body: <p>I have a SQL query that uses a hard-coded value:</p>
  
  
  
  <pre><code>select col1, col2, 'some hard coded value' as col2  
  from table_a  
  union all  
  select col1, col2, col3  
  from table_b
  </code></pre>
  
  <p>I tried the following in SQLAlchemy:</p>
  
  <pre><code>result = session.query(table_a.col1, table_a.col2, 'hardcoded value'.label('col3')
  </code></pre>
  
  <p>but got an <code>AttributeError</code>, which makes sense.  I also thought about adding the value in Python then doing the union.</p>
  
  <p>How can I add this hard coded value to a SQLAlchemy query?</p>