title: Standard sql subquery to ActiveRecord Relation, is it possible?
body: <p>I've got a piece of code where I have to applies some subqueries. I'm trying to change this piece of pure sql to more rails way. Is it possible to implement ActiveRecord Relation here?</p>
  
  <pre><code>Customer.joins("RIGHT JOIN customers_users ON customers_users.customer_id = customers.id").
           where("customers_users.user_id IN (
                                      SELECT user_id FROM customers_users
                                      GROUP BY customers_users.user_id
                                      HAVING COUNT(customers_users.user_id) = 1)")
  </code></pre>