"Ugo" method for tunneling with self-join tables
I have a database with a dashboard on which I would like to display certain product data, but only if we have inventory of that product. In the past I've done this by creating a portal to all products and filtering / sorting the portal. I've found, recently, though, that filtering and sorting portals can perform quite badly; especially over the network. With FM Go it gets pretty gnarly.
I've found that accomplishing these tasks in the relationship map can provide better performance. So, I tried to accomplish the task with what I understand to be called the "ugo" method. My set up is like this:
DASHBOARD Products Products 2
one -------> one
INV_is_not_zero ------> product_id
INV_is_not_zero is defined as a calculation that looks something like this:
if(inventory>0; product_id; 0)
In case it matters, the "inventory" field is also a calculation.
so, i put a portal on the dashboard to "products 2" and I expect it to display all products for which inventory > 0. But it doesn't display anything. I've gone out of my way here to make the calculations land on the initiating side of the relationship. What went wrong?
THanks for your help!