Inventory management / how to handle items that are sold both in packs and as loose items in database design

Question

I request help from experts. In designing inventory management system, I have to store items which are purchased in packs (with 50 / 100/ 200 items) but are sold both in packs or in loose items say 5 or 10. How do I store such items in database? In other words, when items are sold in loose quantities, how we account in stock? Usually this price is not same as the price of packet. This creates problem for assigning selling price as well as updating stock. Thanks in Advance

Answer 1

In all inventory systems, there is a basic Entity called: Measurement Unit

Each item that can be sold, should have relationship with Measurement unit Entity. For example you can sold 1 pack of eggs (or one by one).

So, in your system, you should store all possible measurement units per item.

Additionally , You should store all conversion between measurement units per item. For example 1 pack of eggs = 8 eggs.

here a data model: