Обсуждение: Return 30% of results?
Is there a way to return a percentage of the rows found? I tried window functions but get an error... ERROR: syntax error at or near "OVER" SELECT id, cume_dist FROM ( SELECT id, cume_dist() OVER (ORDER BY id) FROM employees ) s WHERE cume_dist < 0.3
Nick wrote on 18.09.2009 23:31: > Is there a way to return a percentage of the rows found? I tried > window functions but get an error... > > ERROR: syntax error at or near "OVER" > > SELECT id, cume_dist FROM ( > SELECT id, cume_dist() OVER (ORDER BY id) FROM employees > ) s > WHERE cume_dist < 0.3 > Works for me. Are you sure you are using Postgrs 8.4? (Windowing functions are not available in earlier versions) Regards Thomas
//Display the top 40 % of rows in BB_DEPARTMENTHTH
SQL> select ROWNUM,ID FROM EMPLOYEES WHERE ROWNUM < .3*(SELECT COUNT(ID) FROM BB
_DEPARTMENT) GROUP BY ROWNUM,ID;
ROWNUM
----------
1
Martin Gainty
______________________________________________
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> From: nboutelier@gmail.com
> Subject: [GENERAL] Return 30% of results?
> Date: Fri, 18 Sep 2009 14:31:29 -0700
> To: pgsql-general@postgresql.org
>
> Is there a way to return a percentage of the rows found? I tried
> window functions but get an error...
>
> ERROR: syntax error at or near "OVER"
>
> SELECT id, cume_dist FROM (
> SELECT id, cume_dist() OVER (ORDER BY id) FROM employees
> ) s
> WHERE cume_dist < 0.3
>
> --
> Sent via pgsql-general mailing list (pgsql-general@postgresql.org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-general
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On Fri, Sep 18, 2009 at 07:54:30PM -0400, Martin Gainty wrote: > > //Display the top 40 % of rows in BB_DEPARTMENT > > SQL> select ROWNUM,ID FROM EMPLOYEES WHERE ROWNUM < .3*(SELECT COUNT(ID) FROM BB > _DEPARTMENT) GROUP BY ROWNUM,ID; > > ROWNUM > ---------- > 1 > HTH > Martin Gainty That's Oracle, not PostgreSQL. Are you really trying to help here? Cheers, David. -- David Fetter <david@fetter.org> http://fetter.org/ Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter Skype: davidfetter XMPP: david.fetter@gmail.com Remember to vote! Consider donating to Postgres: http://www.postgresql.org/about/donate
On Sep 18, 3:40 pm, spam_ea...@gmx.net (Thomas Kellerer) wrote: > Nick wrote on 18.09.2009 23:31:> Is there a way to return a percentage of the rows found? I tried > > window functions but get an error... > > > ERROR: syntax error at or near "OVER" > > > SELECT id, cume_dist FROM ( > > SELECT id, cume_dist() OVER (ORDER BY id) FROM employees > > ) s > > WHERE cume_dist < 0.3 > > Works for me. Are you sure you are using Postgrs 8.4? > (Windowing functions are not available in earlier versions) > > Regards > Thomas > > -- > Sent via pgsql-general mailing list (pgsql-gene...@postgresql.org) > To make changes to your subscription:http://www.postgresql.org/mailpref/pgsql-general Yeah, im actually not using 8.4. Any other alternatives?
On Sat, Sep 19, 2009 at 12:27:10AM -0700, nick wrote: > On Sep 18, 3:40 pm, spam_ea...@gmx.net (Thomas Kellerer) wrote: > > Nick wrote on 18.09.2009 23:31:> Is there a way to return a percentage of the rows found? I tried > > > window functions but get an error... > > > > > ERROR: syntax error at or near "OVER" > > > > > SELECT id, cume_dist FROM ( > > > SELECT id, cume_dist() OVER (ORDER BY id) FROM employees > > > ) s > > > WHERE cume_dist < 0.3 > > > > Works for me. Are you sure you are using Postgrs 8.4? > > (Windowing functions are not available in earlier versions) > > > > Regards > > Thomas > > > > -- > > Sent via pgsql-general mailing list (pgsql-gene...@postgresql.org) > > To make changes to your subscription:http://www.postgresql.org/mailpref/pgsql-general > > Yeah, im actually not using 8.4. Any other alternatives? The easiest way would be to upgrade to 8.4 because the workarounds for previous versions are complicated and bug-prone. Cheers, David. -- David Fetter <david@fetter.org> http://fetter.org/ Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter Skype: davidfetter XMPP: david.fetter@gmail.com Remember to vote! Consider donating to Postgres: http://www.postgresql.org/about/donate
On Sat, Sep 19, 2009 at 3:27 AM, nick <nboutelier@gmail.com> wrote:
> On Sep 18, 3:40 pm, spam_ea...@gmx.net (Thomas Kellerer) wrote:
>> Nick wrote on 18.09.2009 23:31:> Is there a way to return a percentage of the rows found? I tried
>> > window functions but get an error...
>>
>> > ERROR: syntax error at or near "OVER"
>>
>> > SELECT id, cume_dist FROM (
>> > SELECT id, cume_dist() OVER (ORDER BY id) FROM employees
>> > ) s
>> > WHERE cume_dist < 0.3
>>
>> Works for me. Are you sure you are using Postgrs 8.4?
>> (Windowing functions are not available in earlier versions)
Using 8.3? You can use arrays to stack a set and then pull some records out:
create or replace function some_employees() returns setof employee as
$$
declare
employees_arr employees[];
n_found int;
n_returned int;
begin
select array
(
select employees from employees
where x order by y
) into employees_arr;
n_found := array_upper(employees_arr, 1);
n_returned := n_found * 0.3;
return query select (e).* from unnest(employees_arr[1:n_returned]) as e;
end;
$$ language plpgsql;
couple notes:
*) 8.3 has doesn't have unnest, but it can be made (google array_explode).
*) probably some typos in above...i didn't test it
*) needs some error checking
*) not scalable to huge numbers of records
*) 8.4 can do this much easier!
merlin