retrieve on hand quantity

SELECT SUM (target_qty) , item_idFROM (SELECT moqv.subinventory_code subinv , moqv.inventory_item_id item_id , SUM (transaction_quantity) target_qty FROM mtl_onhand_qty_cost_v moqv WHERE moqv.organization_id = :org_id AND moqv.inventory_item_id = :item_id GROUP BY moqv.subinventory_code , moqv.inventory_item_id , moqv.item_cost UNION SELECT mmt.subinventory_code subinv , mmt.inventory_item_id item_id , -SUM (primary_quantity) target_qty FROM mtl_material_transactions mmt , mtl_txn_source_types mtst WHERE mmt.organization_id = :org_id AND transaction_date >= TO_DATE (:hist_date) + 1 AND mmt.transaction_source_type_id = mtst.transaction_source_type_id AND mmt.inventory_item_id = :item_id GROUP BY mmt.subinventory_code , mmt.inventory_item_id) oqGROUP BY oq.item_id