Need help with getting the previous month data

[#1]

Please see the attached sample. I have a table that has the following fields.

Department,

AccountNumber,

ReportMonth,

Premium,

Dropped,

TotalDCN

I am trying to calculate previous month (DCN and Dropped). The table has two months april and may. I am using may as the current month. The DCN %calculation is (sum(totalDCN)/ sum(premium) and for Dropped % it is (sum(Drop)/sum(Premium).

I want to be be able to select a month and get the DCN% for that month as the current and for the previous to be able to peek and look at the value for the previous month and do the calculation.

For Current Month Only NTK Premium, the value is the sum of the Dropped field where that account number is not in the previous month data. 

Can someone help with this.

[cesaraccardi · Accepted solution]

Hi, here is a suggestion attached.

[#3]

it worked, thanks