How to calculate due date from invoice date and payment terms

Hi,

I Have a requirement of creating FIAR Ageing Report, in that i want to calculate Due date and based on that due date we can populate value un ages

For doing that first i need to calculate Due date based on invoice date and payment terms.

customer         Invoice date   Payment Terms   Due date      

  0001               01.12.2014        R007                01.01.2015    assume here payment term for customer is 1 month

0002                10.12.2014        R003                25.12.2014    assume payment term is 15 days

like that i need to get due date based on payment terms and invoice date for customer.

Pls let me know how to calculate due date based on these whether to calculate at transformation or at r/3 side or at query level.

pls do in favour to rectify this issue and if there is any code pls let me know.

Thanks in advance.

Seshu