title: Sqlalchemy: postgresql paramstyle for engine.execute()
body: <p>I am connected to postgresql with sqlalchemy. When I try this code:</p>
  
  <pre><code>e = create_engine('')
  r = e.execute("select ?", 5)
  </code></pre>
  
  <p>it gives me: </p>
  
  <pre><code>sqlalchemy.exc.ProgrammingError: (ProgrammingError) syntax error at end of input
  </code></pre>
  
  <p>Corresponding to <a href="http://www.sqlalchemy.org/docs/core/connections.html?highlight=engine#sqlalchemy.engine.base.Connection.execute" rel="nofollow">http://www.sqlalchemy.org/docs/core/connections.html?highlight=engine#sqlalchemy.engine.base.Connection.execute</a> there are different types of paramstyles... 
  After deeper research, i found out that default paramstyle for postgresql Dialect is "pyformat". </p>
  
  <p>Can somebody show me how to use this pyformat on some example?
  I would just like to use placeholders or named placeholders for forming up the sql statement. </p>
  
  <p>I tried:</p>
  
  <pre><code>e.execute("select %s, %s;", "test", "test2")
  </code></pre>
  
  <p>But this is not working either.</p>
  
  <p>Thank you</p>
  
  <p>edit:
  of course, i am passing valid connection string to create_engine method :-)</p>