Database Design: Inventory with multilevel packaging - sql

Question

I'm trying to develop a database for my inventory. But I have no idea how to keep track of multilevel packaging.
For example:
I currently have a products and positions table
products
Id | Name
================
1013 | Metal
1014 | Wood
positions
id | Name
================
1 | 1-1-1-1
2 | 1-1-1-2
And my inventory table I was thinking of doing something like this:
Let's say I stored 1 box with 1000 Metal and 1 box with 500 Wood at position 1-1-1-1
ItemId | ProductId | Quantity | PositionId
==========================================
1 | 1013 | 1000 | 1
2 | 1014 | 500 | 1
So I'll label those two boxes with a barcode 1 and 2 respectively, so if I scan them, I can check this table to see the product and quantity inside them.
But I can also put these 2 boxes (1 and 2) inside another box (let's call it box 3), which would generate a new barcode for it that, if scanned, will show both previous boxes and its items. And store this box 3 in another position
And I can also put this box 3 inside a pallet, generating a new code and so on. So basically I can multilevel package N times.
What is the best table structure to keep track of all of this? Thanks in advance for any help!

Answer 1

I would add another column to the products table, make it a BIT and maybe call it BOM, BillOfMaterials, or whatever makes sense to you
So your products Table would look like this
Then you could create another table called BillOfMaterials
Quantity is how many of your products are needed to make up your new product. So for this example 2 metal and 1 wood make a pencil.

Answer 2

I was able to make a good structure:
My products and positions are the same but I created a stock table like:
id | product_id | amount | parent_id | position_id
=====================================================
1 | 1013 | 1000 | 4 | 1
2 | 1013 | 1000 | 4 | 1
3 | 1014 | 500 | 4 | 1
4 | 1234 | NULL | NULL | 1
The 1234 (random id) is a box that contains 2000 metal and 500 wood. I dont save this box in the product table.
When I scan the box with id 3, I perform a recursive cte query:
with recursive bom as (
select *, 1 as level
from testing.stock
where id = '4' #scanned id
union all
select c.*, p.level + 1
from testing.stock c
join bom p on c.parent_id = p.id
)
select product_id as product, sum(amount), position_id
from bom b
left join testing.product pd on b.product_id = pd.id
where pd.id is not null
group by product_id, position_id
which returns:
sum | product | position
2000 | 1013 | 3
500 | 1014 | 3
to get by position I just run a variation of the above query. To perform an update I get the Ids inside that box and run a
update testing.stock set position = '2' where id in (#variation of above query)
I hope this helps someone. This works for N packaging level