functions and list

[Nicolas Dufour <ni...@neometsys.fr>]

Hi

I wonder how I can create an aggregate function like count or max ?
The idea is i want to process in the same time a list of row and return 
something.
For example, I need to get from a list of flights (rows of table flight) 
the average delay.

Is it possible in Derby and how ?

Thank you

Nicolas

Re: functions and list

[Michael Segel <ms...@segel.com>]

On Wednesday 02 November 2005 10:09, Rick Hillegas wrote:
Sorry to top post. 
(I know just how important net etiquette is these days... ;-)


> Hi Nicolas,
>
> In old releases of Cloudscape, customers were able to create their own
> aggregates. This functionality was removed from Derby probably because
> the syntax was considered non-standard. Most of the machinery for this
> feature is still in the code and it should be easy to re-enable once we
> agree on acceptable syntax. I have logged enhancement request 672 to
> track this issue.
>
> Regards,
> -Rick
>
Uhmmm I'm not sure its a question of user defined aggregates. The question was 
AVG, MAX, pretty much the norm.

I'm looking at the version 10 doc (dated Apr 12 2005) [Reference Manual]
and there seems to be a whole slew (beaucoup), of built in functions?

Among them... MAX, COUNT, AVG, SUM, ... well you get the idea.

Now its a pity that you removed extensibility. I guess the question is, should 
Derby be like other databases that contain extensions to SQL92?
But thats another story... ;-) 

> Nicolas Dufour wrote:
> > Hi
> >
> > I wonder how I can create an aggregate function like count or max ?
> > The idea is i want to process in the same time a list of row and
> > return something.
> > For example, I need to get from a list of flights (rows of table
> > flight) the average delay.
> >
> > Is it possible in Derby and how ?
> >
> > Thank you
> >
> > Nicolas
Interesting that you chose airlines. Thats the examples found in the reference 
manual.


-- 
Michael Segel
Principal 
MSCC

Re: functions and list

[Rick Hillegas <Ri...@Sun.COM>]

Hi Nicolas,

In old releases of Cloudscape, customers were able to create their own 
aggregates. This functionality was removed from Derby probably because 
the syntax was considered non-standard. Most of the machinery for this 
feature is still in the code and it should be easy to re-enable once we 
agree on acceptable syntax. I have logged enhancement request 672 to 
track this issue.

Regards,
-Rick

Nicolas Dufour wrote:

> Hi
>
> I wonder how I can create an aggregate function like count or max ?
> The idea is i want to process in the same time a list of row and 
> return something.
> For example, I need to get from a list of flights (rows of table 
> flight) the average delay.
>
> Is it possible in Derby and how ?
>
> Thank you
>
> Nicolas