I have a set of data that includes a field with the datetime that events happen. i want to group the events by month. I haven't come across a simple and elegant expression to achieve this. So far all I can come up with is to convert the field to a date, then take the year and month as integers and then convert this back to a string with the day set to 1. In Crystal Reports I would group on the datetime field and then set the period to month, very easy.

I am sure there is an easy answer to this that I haven't been able to find.