Is there a way to group by monthly period? : <p>I have data that I need to query to find out which person spent the most over a 9 month period. My data spans 5 years and the 9 month period may consist of months from one year and through the next year.</p>

<p>For example October 2005 through July 2006.</p>

<p>I've managed to group by personid and month and year, but is there a way for me to group by 9 month periods? I figured if I can do that then I can just find the max value in that grouping.</p>
