Re: Horizontal aggregation?

On Sat, Apr 14, 2012 at 1:22 AM,  <hamann.w@t-online.de> wrote:
>
>
> Hi,
>
> I am looking for a feature that would select from a table with
> k1  a
> k1  b
> k1  c
> k2  a
> k3  b
> k3  c
> something like
> k1  a b c
> k2  a
> k3  b c
> (Just all elements next to each other, with a space in between)
> or perhaps an array output
> k1  {a,b,c]
> k2  {a}
> k3  {b,c}
>
> If such an operator exists, would there be a "remove duplicates" option?
>
> Regards
> Wolfgang Hamann
>
>
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select k, array_agg(distinct val ) from t;

See the docs: http://www.postgresql.org/docs/9.1/static/sql-expressions.html#SYNTAX-AGGREGATES