s are processed by
    window functions using <code class="literal">ORDER BY</code> within <code class="literal">OVER</code>.
    (The window <code class="literal">ORDER BY</code> does not even have to match the
    order in which the rows are output.)  Here is an example:

</p><pre class="programlisting">
SELECT depname, empno, salary,
       rank() OVER (PARTITION BY depname ORDER BY salary DESC)
FROM empsalary;
</pre><p>

</p><pre class="screen">
  depname  | empno | salary | rank
-----------+-------+---