I don't think that the error that you got is an error that is generated from SQL Server. I couldn't find an error with similar text and you didn't supply an error number. In any case, you can use a trigger to update table that has no primary key from that trigger update one or few records from the same table. The code bellow does that:

use tempdb

go

--Creating the table

create table Demo (i int, j int, TimeUpdated datetime)

go

--Creating the trigger

create trigger DocumentUpdateTime

on Demo

for update, insert

as

--Doing an update without using varibles.

--More recommended because the update

--can effect many rows

update Demo

set TimeUpdated = getdate()

from Demo inner join Inserted

on Demo.i = Inserted.i and Demo.j = Inserted.j

go

insert into Demo (i, j)

select 1,1

union all

select 1,1

union all

select 1,2

go

update Demo set j = 4 where j = 2

go

waitfor delay '00:00:01'

update Demo set j = 3 where j = 1

go

--Notice that the value of TimeUpdated

select * from Demo

update Demo set j = 1

--Notice that again it modified the column

--TimeUpdated. If I was using varibles,

--it would update some of the records

select * from Demo

go

drop table Demo

By the way – why don't you have a primary key? You should have one.

Adi