title: How to map count of collection to entity with fluent-nhibernate
body: <p>With employees and subordinates - I want to load an employee with the count of subordinates in one query.</p>
  
  <pre><code>public class Employee
  {
      public Name {get;set;}
      public int NumberOfSubordinates {get;set;}
  }
  </code></pre>
  
  <p>Resulting SQL should look like : </p>
  
  <pre><code>select e.name, (select count(*) from subordinate s where s.employee_id = e.id) NumberOfSubordinates
  from employee e 
  group by e.name
  order by NumberOfSubordinates desc
  </code></pre>