title: HQL Path expected for join (when joining same table)
body: <p>I am trying to get pairs of measurement for two different devices, joined on equal Timestamps. In SQL, this works as expected:</p>
  
  <pre><code>select
    leftItem.Timestamp, leftItem.Value, rightItem.Value
  from
    DataTable leftItem
    inner join DataTable rightItem
    on leftItem.Timestamp = rightItem.Timestamp
  where
    leftItem.Device = 1 and rightItem.Device = 2
  </code></pre>
  
  <p>But if I try to convert it to HQL:</p>
  
  <pre><code>select
    left, right 
  from
    DataTable as left 
    inner join DataTable as right
    on left.Timestamp = right.Timestamp
  where
    left.Device = 1 and right.Device = 2
  </code></pre>
  
  <p>I get a <code>NHibernate.Hql.Ast.ANTLR.SemanticException:</code></p>
  
  <pre>
  Path expected for join!
  </pre>
  
  <p>How do I specify a "path" to the same table?</p>