Update After A Change

Hi,

I have two tables (test, test_invoice) both filled in automatically; what i need to do is update whenever there has been a change in table test_invoice (literally new record with date of invoice).

two tables:

create table test
(id_customer int not null
,date1 smalldatetime
,date2 smalldatetime
,flag char(3)
)
ALTER TABLE [dbo].[test] ADD
CONSTRAINT [PK_test] PRIMARY KEY CLUSTERED
(
[id_customer]
) ON [PRIMARY]
GO

insert into test (id_customer, date1, date2, flag) values (2323, '2008-2-23', '', 'Yes')
insert into test (id_customer, date1, date2, flag) values (2325, '2008-2-25', '', 'No')

create table test_invoice
(id_customer int not null
,date_invoice smalldatetime
)

ALTER TABLE [dbo].[test_invoice] ADD
CONSTRAINT [PK_test_invoice] PRIMARY KEY CLUSTERED
(
[id_customer]
) ON [PRIMARY]
GO

insert into test_invoice (id_customer, date_invoice) values (2325, '2008-3-2')
insert into test_invoice (id_customer, date_invoice) values (2329, '2008-3-5')


so how do i make this update happening automatically whenever there is a new record in test_invoice

update t
set t.date2 = ti.date_invoice
from
test as t
inner join test_invoice as ti
on ti.id_customer = t.id_customer


I'd say IF is missing in front of the update sentance...? :-)

Thank you