On 02/03/2023 20:58, Ron wrote:
> Postgresql 12.13
>
> Given the sample below, I'm looking for how to generate this output.
> It's like GROUP BY, but generating an array instead of an aggreate number.
> f1 | f2_array
> ----+---------
> 1 | {1,2,3}
> 2 | {1,2,3,4}
> 3 | {1,2}
Something like this (off the top of my head)? -
select f1, array_agg(f2) as f2_array group by f1;
Hope that helps (and that it's right!).
Ray.
>
> The ultimate goal is to somehow use pg_index.indkey to get column names
> from pg_attribute.
>
> create table foo (f1 int, f2 int);
> insert into foo values (1, 1);
> insert into foo values (1, 2);
> insert into foo values (1, 3);
> insert into foo values (2, 1);
> insert into foo values (2, 2);
> insert into foo values (2, 3);
> insert into foo values (2, 4);
> insert into foo values (3, 1);
> insert into foo values (3, 2);
>
> select * from foo order by f1, f2;
> f1 | f2
> ----+----
> 1 | 1
> 1 | 2
> 1 | 3
> 2 | 1
> 2 | 2
> 2 | 3
> 2 | 4
> 3 | 1
> 3 | 2
> (9 rows)
>
>
>
--
Raymond O'Donnell // Galway // Ireland
ray@rodonnell.ie
