tpb_hitung_saldo_awal function

create function tpb_hitung_saldo_awal (transaction_id integer, product_id integer, locator_id integer)
    returns integer  as $func$
begin
    return  (
    select sum(movementqty) into qty from m_transaction mt
    where m_transaction_id <= transaction_id
        and m_product_id = product_id
        and m_locator_id  = locator_id
    );
end $func$
LANGUAGE PLPGSQL;