Hi [@Vittorio](/u/vitweb)

See the `sma_purchase_items` table as the main inventory table for the SMA system. It has a `quantity` column, a `quantity_balance` column, and reference ID columns for Purchases and Transfers columns, among other columns.
All completed **stock-In** [purchases, positive-adjustment (addition), transfer IN/TO warehouse (product quantity-add-up)] get **added up** to the product quantity in here; the same goes for all your **stock-Out** (sales, transfer OUT/FROM (deduction), negative-adjustment (subtraction), they get **deducted** from the product quantity in here.
The `quantity` column reflects the quantity of stock-in, while the `quantity_balance` column reflects what is remaining.


My name is [@Enyinnaya Gift](/u/giftedhands4real) . I am an `Independent software developer` with in-depth knowledge of SMA system. I have done a lot of customization for many happy clients across the globe.

You can check out highlights and a demo of my latest customization by [Clicking HERE - Highlights](https://sma.gehandsitsolutions.com/admin/highlights)

You can also reach me via any of the following mediums for a real-time discussion on your customization request:

-Skype ID: `enyinnayag`
-Wechat ID: `genyinnaya`
-Email: `[email protected]`
-WhatsApp: `+2348068355192`

Hello,

As [@Enyinnaya Gift](/u/giftedhands4real) explained. The quantity is tracked using purcahse items table. The quantity file on products table is symbolic repersentation that get update from purcahse items's quantity balance value.

Thank you