Conditional Value List by Non-Indexed Field
I am making a basic inventory system. For our purposes let's say I have the following tables: "Inventory", "Inventory Depletion", "Inventory Addition", and "Build". The "Inventory" table contains the actual inventory record. In "Inventory" the remaining amount is calculated by subtracting the sum of the amounts in all related "Inventory Depletion" records from the amount in the related "Inventory Addition" record. In "Build" you select an inventory item from a drop down (the value list consists of the Inventory ID field in "Inventory") and pull a specified amount into the recipe you are building by creating an associated "Ingredient Depletion" record from the "Build" layout with a script. I want the drop down list in "Build" to contain only the Inventory ID's for the "Inventory" records which have remaining amounts greater than zero. The fact that the values for the remaining amounts in the "Inventory" records are not indexed is creating issues for me. What is the proper way to do this?