Hi Ice72 ,
No, we haven't a schema, sorry.
Anyway, I've been taking a quick look at your SQL query, and even though it's out of the scope of our free support, I can give you some guidance:
1. We don't use the woocommerce_order_items table, try with atum_order_items.
2. atum_inventory_orders has an order_type field that we use to distinguish between ATUM and WC orders.
We've just released a new ATUM addon that will export all this data for you.
Hope this helps,