pg.ddx.io pgsql-sql@postgresql.org mailing list archive
help / color / mirror / Atom feedCombining values in a column
2+ messages / 2 participants
[nested] [flat]
* Combining values in a column
@ 2005-04-15 09:22 Stephen Quinney <stephen.quinney@computing-services.oxford.ac.uk>
2005-04-15 10:12 ` Re: Combining values in a column Sean Davis <sdavis2@mail.nih.gov>
0 siblings, 1 reply; 2+ messages in thread
From: Stephen Quinney @ 2005-04-15 09:22 UTC (permalink / raw)
To: pgsql-sql
I have a query which returns a single column of integers which I want
to combine together with &, "bitwise AND". Basically it's a simple
list of access levels that a user might have and I want to merge the
list into one value. There can be zero, one or more values in the list
so I have to be able to cope with the no-results .
For example
access
--------
31
511
Would lead to 31 & 511 which gives 31.
I guess really this can lead to the more generic question. How do I
apply a general function to combine the values, if I, for example,
wanted to write my own aggregate function like sum?
Thanks in advance,
Stephen Quinney
^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: Combining values in a column
2005-04-15 09:22 Combining values in a column Stephen Quinney <stephen.quinney@computing-services.oxford.ac.uk>
@ 2005-04-15 10:12 ` Sean Davis <sdavis2@mail.nih.gov>
0 siblings, 0 replies; 2+ messages in thread
From: Sean Davis @ 2005-04-15 10:12 UTC (permalink / raw)
To: Stephen Quinney <stephen.quinney@computing-services.oxford.ac.uk>; +Cc: pgsql-sql
See below for creating aggregates:
http://www.postgresql.org/docs/current/static/xaggr.html
But, there is a useful function built-in, bit_and, that does what you
want:
http://www.postgresql.org/docs/current/static/functions-
aggregate.html#FUNCTIONS-AGGREGATE-TABLE
create table testint (
myint int
);
CREATE TABLE
insert into testint values (31);
INSERT 428988938 1
insert into testint values (511);
INSERT 428988939 1
select bit_and(myint) from testint;
bit_and
---------
31
(1 row)
On Apr 15, 2005, at 5:22 AM, Stephen Quinney wrote:
> I have a query which returns a single column of integers which I want
> to combine together with &, "bitwise AND". Basically it's a simple
> list of access levels that a user might have and I want to merge the
> list into one value. There can be zero, one or more values in the list
> so I have to be able to cope with the no-results .
>
> For example
>
> access
> --------
> 31
> 511
>
> Would lead to 31 & 511 which gives 31.
>
> I guess really this can lead to the more generic question. How do I
> apply a general function to combine the values, if I, for example,
> wanted to write my own aggregate function like sum?
>
> Thanks in advance,
>
> Stephen Quinney
>
>
>
>
>
> ---------------------------(end of
> broadcast)---------------------------
> TIP 7: don't forget to increase your free space map settings
>
^ permalink raw reply [nested|flat] 2+ messages in thread
end of thread, other threads:[~2005-04-15 10:12 UTC | newest]
Thread overview: 2+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2005-04-15 09:22 Combining values in a column Stephen Quinney <stephen.quinney@computing-services.oxford.ac.uk>
2005-04-15 10:12 ` Sean Davis <sdavis2@mail.nih.gov>
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox