INVENTORY & ORDER MANAGEMENT Tables join conditions

See below join condition between Inventory & Order Management

SELECT
c.segment1,--Item Name
a.order_number,
b.line_number,
b.shipment_number,
SUM(d.primary_transaction_quantity) as onhand
FROM oe_order_headers_all a,
oe_order_lines_all b,
mtl_system_items_b c,
mtl_onhand_quantities_detail d
WHERE b.header_id = a.header_id
AND b.inventory_item_id = c.inventory_item_id
AND b.ship_from_org_id = c.organization_id
AND b.inventory_item_id = d.inventory_item_id
AND b.ship_from_org_id = d.organization_id
AND b.flow_status_code = 'AWAITING_SHIPPING'
AND d.subinventory_code = 'Warehouse'
GROUP By c.segment1, a.order_number, b.line_number, b.shipment_number
ORDER BY c.segment1