There is primary key. In fact, it isn't strict copy of records. Primary key is generated from gen_id(), and there are some data changes on the fly (in select clause).
But I still wonder why select doesn't take a snapshot :)

Regards, Tomek

--- In firebird-support@yahoogroups.com, Sándor Tamás (HostWare Kft.) <sandortamas@...> wrote:
>
> For tables like this, you definitely should have a primary key, like an auto
> increment field. (By the way, when do you need duplicated datas to be in a
> table without unique identifier? )
>
> With that, you can read the last value, and do a select where PRIMARY_ID <=
> MAX_VALUE.
> (in fact, it will be faster than the null compare for temp_field)
>
> SanTa