There is also a shipping process — they took and moved 5 meat grinders from the region to other regions, to the city. How is this handled?

The process of moving 5 meat grinders from region to region and to the city is usually handled through a warehouse management and logistics system.

Main steps:

1. Inventory update — decrease in the source warehouse and increase in the target warehouses.
2. Creating a shipment document — recording the movement of goods, date, quantity.
3. Tracking status — monitoring whether the goods are in transit, arrived, accepted.
4. Error handling — for example, if part of the goods is damaged or lost.

In Go code, this might look like a transaction where records in the database are atomically updated:

func TransferItems(itemID string, fromRegion string, toRegion string, quantity int) error {
    tx, err := db.Begin()
    if err != nil {
        return err
    }
    defer tx.Rollback()

    // Decrease quantity at the sender's warehouse
    _, err = tx.Exec(`UPDATE inventory SET quantity = quantity - ? WHERE item_id = ? AND region = ?`, quantity, itemID, fromRegion)
    if err != nil {
        return err
    }

    // Increase quantity at the receiver's warehouse
    _, err = tx.Exec(`UPDATE inventory SET quantity = quantity + ? WHERE item_id = ? AND region = ?`, quantity, itemID, toRegion)
    if err != nil {
        return err
    }

    // Create a shipment record
    _, err = tx.Exec(`INSERT INTO shipments (item_id, from_region, to_region, quantity, status) VALUES (?, ?, ?, ?, ?)`, itemID, fromRegion, toRegion, quantity, "in_transit")
    if err != nil {
        return err
    }

    return tx.Commit()
}

This ensures data consistency and the ability to track movements.