This question is more about how inventory is handled in actual practice - not about how to program it in a specific language.

Items may be available in larger and smaller groups. To give an example, a shop may sell a kg. of a certain type of screws, but it may also sell individual screws. Of course, this is just an example. The shop may decide to sell screws only one package at a time - but there may still be a similar situation in the case of other products.

How is this handled for the sale, and updating the inventory, in the computer system? I would imagine that there would have to be a special process where the user must register the "unpacking" of a package, converting, e.g., one kg. of screws into 150 individual screws - or whatever the average number determined for this kind of screw. Then, 1 unit (1 kg. in this case) of one item (the package) would have to be discounted from the inventory, while on the other hand, 150 units (individual screws) would have to be added to another inventory item.

This is the general idea I have, but I have never seen it done in practice, and would be grateful for any advice on how this is usually managed.

TIA,

Hilmar.