title: number formatting mask for to_char()
body: <p>Can you explain the difference between the following queries</p>
  
  <pre><code>SELECT TO_CHAR(1980.55,'$9,999D999') FROM DUAL;
  </code></pre>
  
  <p>and</p>
  
  <pre><code>SELECT TO_CHAR(1980.55,'$9G999D999') FROM DUAL;
  </code></pre>
  
  <p>The first query fails with an error, what I don't understand is that the group separator defaults to ',' so why does one fail and the other execute successfully.</p>