Thanks Jim for your help, I have changed the code provided to suit my DB as:
CREATE TRIGGER [TR_updateColWithDate]
ON [dbo].[tbl_assets]
FOR UPDATE
AS
BEGIN
UPDATE t
SET dateedited = GetDate()
FROM tbl_assets t
INNER JOIN inserted i -- inserted is the actual name
ON t.id = i.id -- (whatever your unique identifier is)
END
the unique identifier is ID (autonumber) but cannot get this work, am I doing something wrong?