--- In firebird-support@yahoogroups.com, Mike Pomraning <mjp@...> wrote:

>
> Is there a technique to make the return value of a UDF constant across
> the execution of a single query?
>
> For example, I'd like getExactTimestamp() -- or, rather, a UDF very
> much like it -- to return the same result every time it is evaluated,
> much like the context variable CURRENT_TIMESTAMP does. Right now, of
> course, the UDF is evaluated over and over, returning a different
> result each time. This effect can be seen if we introduce a function
> (FB_SLEEP()) to pause execution for a second or so with every row in
> the result set:
>
> SQL> select count(1) from threecount;
>
> COUNT
> ============
> 3
>
> SQL> select current_timestamp, getexacttimestamp(), cast('now' as
> timestamp) AS NOW, fb_sleep(1) from threecount;
>
> CURRENT_TIMESTAMP GETEXACTTIMESTAMP
> NOW FB_SLEEP
> ========================= =========================
> ========================= ============
> 2011-03-17 17:52:21.5510 2011-03-17 17:52:22.5511 2011-03-17
> 17:52:22.5510 0
> 2011-03-17 17:52:21.5510 2011-03-17 17:52:23.5511 2011-03-17
> 17:52:23.5510 0
> 2011-03-17 17:52:21.5510 2011-03-17 17:52:24.5511 2011-03-17
> 17:52:24.5510 0
>
> So, can I make an arbitrary UDF instead behave like CURRENT_TIMESTAMP?
> I didn't see a feature request to this effect on the FB tracker, so I
> thought I'd ask here. Thanks.
>
> -Mike
>

Why not use CURRENT_TIMESTAMP?
An why you need do something so wrong like fb_sleep in query?
What is your real interest?


Karol Bieniaszewski