title: handling of numbers in ORDER BY with the CASE statement
body: <p>Numbers in ORDER BY refer to column ordinal position in the SELECT list.
  So the following query is equivalent to ordering by 'C.custid, C.region':</p>
  
  <pre><code>SELECT
  C.custid, C.region
  FROM SALES.Customers AS C
  ORDER BY  1, c.region
  </code></pre>
  
  <p>Now if I make use of a CASE statement such that I want the NULL value in region column to be sorted last, then I would do something like:</p>
  
  <pre><code>SELECT
  C.custid, C.region
  FROM SALES.Customers AS C
  ORDER BY  CASE WHEN C.region IS NULL THEN 1 ELSE 0 END, C.region
  </code></pre>
  
  <p>In this case the numbers are treated not as ordinal position of columns but as hard coded values helping to change the sort order. </p>
  
  <p>If my understanding is correct, why this discrepancy? Reason behind it?</p>
  
  <p>Thanks</p>