title: Oracle SQL Plus WITH Clause "invalid identifier"
body: <p>The database is running on Oracle Database 11g using SQL *Plus 11.2.  Are aggregate methods not allowed in a WITH clause or is WITH doing something magical?  This code tells me "most_expensive" is an invalid identifier.  Yet, a sub-query works with no issue.</p>
  
  <pre><code>WITH most_expensive AS (SELECT MAX (enrollment_cost) FROM Enrollments)
  SELECT e.member_id
  FROM Enrollments e
  WHERE e.enrollment_cost = most_expensive;
  </code></pre>