pls-00049/ View From a Button

1 I have created one table

item_master (item_id varchar2(4)
(sub_item_code varchar2(4)
(description varchar(100)

i have created a form using this table and add a button on this form. I wish to view all records of this table (on pressed) using this created button on this form. How to do

2. I have created two tables
a.) item_master (item_id varchar2(4)
sub_item_code varchar2(4)
description varchar2(100)

b.) audit_cust (item_no varchar2(4)
description varchar2(100)
i have createds a trigger as given below

create or replace trigger viewall
before update on item_master
for each row
--declare
--description varchar2(100);
begin
insert into audit_cust values (:old.description);
end;

when compiling it shows erros. I have tried with both the option i.e removing declare & without removing declare. In both the cases it show erros as

4/32 PLS-00049: bad bind variable 'OLD.DESCRIPTION'

pl help

(navneet)

sorry, just deleting.