Extracting invoice information into a client database

[Sal]

Hi,

I am looking for some help with the following:
I have an invoice template which I create client invoices from and I have a
client database containing address details etc.

Firstly, each time I create an invoice I would like the invoice number and
the invoice total to pass back to the client database.

Secondly I would like to find some way of amalgamating the total of the
monthly invoices up and creating a statement at the end of each month for
each client.

Can anyone point me in the right direction.

Many thanks