Sum items in a portal
I have an "invoice" table that pulls from an "invoice items" table and these two are connected on the "invoice number."
What I want to do is simple and I thought I'd be able to figure it out or find it in the forum, but I haven't. When I am viewing a layout that displays details of one invoice, it shows a portal that pulls in all of the "invoice items" that have that same "invoice number." I want to have a "Total" field that automatically sums the prices of all of these invoice items.
I figured this would be a calculated field that would sum all of the "invoice item" records with the same invoice number. When I try and mess around with it, however, I'm not exactly sure how to specific that, and I also am unsure if I need to use "If" or just "Sum."
Any help would be greatly appreciated.