from/ to selection in query designer

Dear all,

I want to have the end value of a certain period of time. In the example below I show you what I mean: (As an example I want to see the value of the period 11.2006-03.2007)

for the period 11.2006 I want to have the sum of 1.2006,2.2006,...,10.2006,11.2006

for the period 12.2006 I want to see the sum of 1.2006,2.2006,...,11.2006,12.2006

for the period 01.2007 I want to have the sum of 01.2007

for the period 02.2007 I want to have the sum of 01.2007+02.2007

for the period 03.2007 I want to have the sum of 01.200702.200703.2007

(as an end value I want to see the sum of all values together.)

There are offset values available for previous year to date and year to date.

Is there an opporunity to make a kind of formula for this issue? Where I can insert an from/ to selection and the system makes a sum of all the values like in my example above?

I don't want a formula only for this selection, but for any other selection like from 02.2006 to 05.2006 or from 04.2006 to 06.2007.

Hopefully someone knows the answer to my question!?

Thanks in advance,

Jens Bevers