Re: Re: select distinct - Mailing list pgsql-general

From newsreader@mediaone.net
Subject Re: Re: select distinct
Date
Msg-id 20010812212131.A29895@dragon.universe
Whole thread Raw
In response to Re: select distinct  (newsreader@mediaone.net)
List pgsql-general
That's beautiful!

Thanks a lot.



On Sun, Aug 12, 2001 at 06:14:35PM -0700, Stephan Szabo wrote:
>
> On Sun, 12 Aug 2001 newsreader@mediaone.net wrote:
>
> > Never mind.  I figure out that what
> > I am asking is not possible
>
> If you're willing to use a postgres extension, you
> can do (this is the 7.1 syntax, you can do it on
> at least 7.0, but it's a little different):
> select distinct on (i) i,a from a where c=2;
> (Warning: without an order by, this statement
> is not guaranteed to give the same results twice
> for the same dataset)
>
> If you know you always want a minimum/maximum a
> for each i (if there is more than one a per i),
> you can probably do this more standardly with
> group by, something like:
> select i, min(a) from a where c=2 group by i;
>
> > On Sun, Aug 12, 2001 at 08:39:35PM -0400, news wrote:
> > > It seems that I cannot get other columns
> > > with distinct in the select statement.
> > >
> > > I want to do like
> > >     select distinct i,a from a where c=2;
> > >
> > > Right now I have to do
> > >     select distinct i from a where c=2
> > > and then iterate over each i to get a
> > >
> > > I have also tried
> > >     select a,distinct i from a where c=2
> > >
> > > I would appreciate any suggestion

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