title: how to use select and extract date into month and year from timestamp in sequelize ORM?
body: <p>I have this query in sql:</p>
  
  <pre><code>select to_char (created_at,'Mon') as month,
  extract (year from created_at) as year,
  id_activity as activity
  from event
  group by 1, 2, 3
  </code></pre>
  
  <p>i tried something simple at first, like this to help my understading:
  <code>model.findAll({attributes: [[ sequelize.fn('extract(year)', sequelize.col('created_at')), 'data']] })</code></p>
  
  <p>but it does not work.</p>
  
  <p>i'm using postgresDB </p>