Change dropdown list based on calendar control

Hi i have a dropdown list which returns values from the database in this format; Month Year e.g December 2008. I also have a popup calendar control, what i want to do is when a date is clicked on the calendar control it then changes the dropdown list value to the correct date e.g if on the calendar control you click on a date in january, it then changes the dropdown list value to January 2009, is this possible?
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