Function to Get PO Order Qty

CREATE OR REPLACE function getpoordqty(p1 in number) return number as
  v_qty number;
begin
  SELECT NVL(SUM(b.QUANTITY), 0)
    into v_qty
    FROM rcv_shipment_lines a, po_line_locations b
   WHERE a.PO_LINE_LOCATION_ID = b.LINE_LOCATION_ID
     AND a.SHIPMENT_LINE_ID = p1;
  return v_qty;
exception
  when no_data_found then
    return null;
end;
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