Help with finding difference between two listboxes

[#1]

Hi All,

Can someone guide me to the right formula I can use to find the difference of values between the two listboxes? I want to be able to analyze the difference between Nov and Dec. I am using expression within the listboxes to get the customer ids in the two respected months. e.g. if(month=12, customerid). I have tried every formula and filtering in the book but the difference doesn't show. They two months have formed a some kind of a array where the difference doesn't budge.

Thanks in advance.

[swuehl]

Maybe using a field expression like

=Aggr(Only({<customerid = p({<month ={11}>}) / p({<month = {12} >}) >} customerid), customerid)

[#3]

Hi Swuehl,

That formula works great. It provides me with the difference of the customer ids for both Nov and Dec. Is there anyway I can only find the customer ids missing in the month of Nov that are present in the month of Dec or the vice versa?

Thanks in advance

[erikzions]

If it doesn't have to be a list box, you can use a straight table.  First column for Nov. Second for Dec.  Then a third to get the difference. 

[swuehl · Accepted solution]

=Aggr(Only({<customerid = p({<month ={12}>}) -  p({<month = {11} >}) >} customerid), customerid)

[#6]

Thank you everyone for your wonderful and timely feedback.