Invoices and orders

[eluser]FcbInfo[/eluser]
Hello. Is possible to do with CodeIgniter an aplication like that demo.simpleinvoices.org ?

When you go to edit an invoice you can ADD ROW (invoice item) and REMOVE ROW, inside a invoice with customer data and invoice data.

That use 2 tables... invoces and invoice_itens.

It's hard to do, or i can get this working with user guide?

Thank you!