How to solve stock calculation Error?

[Rohullah]

Hello
I have to two tables as following
-----------------------------
create table orders
(orderid number primary key,
orderdate date,Ename varcarh2(20),
ItemID number,ItemName varchar2(20),
Itemtype varchar2(20),to ns number);
sql>table created

create table companystock
(Itemid number,ItemName varchar2(20),
Itemtype varchar2(20),to ns number);
sql>table created
-----------------------------
when i create primary key on companystock.it emid
reference it to orders.itemid then
in the form6i I create abutton by the name of Save Record
and i do the following code for the button
WHEN-BUTTON-PRESS trigger
----------------------------
begin
if nvl(:orders.ite mid,0)=:company stock.itemid then
update companystock set tons=tons+nvl(: orders.tons,0)
where itemid=:orders. itemid;
ELSIF nvl(:orders.ite mid,0)<>:compan ystock.itemid then
insert into companystock(it emid,itemName,i temtype,tons)
values
(:orders.itemid ,:orders.:itemn ame,:orders.:it emtype,:orders. tons);
commit_form;
go_block('order s');
execute_query;
end if;
exception when others then
message('Record Not Saved Successfull');
end;
--------------------------------
it insert record but it not update the record;
if i remove the primary key from companystock.it emid then
it insert duplicate record into companystock.
PLZ give me the best passible way to solve the problem.

Looking forword.
thank u in advance.

[Jaydeep Paul]

commit_form; is local for elsif block. In the if block it is doing the task but not getting commited.