Subsummery calulation for inventory
I'm currently working on a grain inventory data base. I'm having a hard time coming up with a "sumif" type function to properly track what comes into and leaves the system all while having a real time sum of the difference.
My current design consists of an "Interim" table where all purchases are entered (Fields calculated: Type, Net_weight).
On the flip side, I have a "Sales" table where all out going sales are done (Fields calculated: Type, Quantity).
I'm trying to get an Inventory page working where I can have a real time idea of how much product we currently have in house.
So far I was able to get the "TypeSumField" (here) trick working but this breaks when I delete a ticket. The total is only correct when a change is made to the particular grain type either on a new ticket or an old one.
Help will be GREATLY appreciated!