Calculations with summary field
I have two tables, and a layout for each. One with inventory information, and the other with customer transactions. I have i have a filtered portal in the inventory layout that shows the transactions for that specific item in the inventory. The filter is inventory::item number = customer transactions::item number. within the same portal, i have a summary field which indicates how many items total have been used in transactions by calculating the sum of the "quantity" field in the transactions.
What I want, is to have a field that calculates the remaining inventory, by subtracting the quantity in that summary field, from the starting quantity. It works perfectly, provided there are transactions and the summary field is not empty. However, if there haven't been any transactions, and therefore the summary field is empty, this remaining inventory field will simply be empty. Is there a simple fix for this?