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From: Paul A Jungwirth <pj@illuminatedcomputing.com>
Date: Mon, 9 Mar 2026 15:05:17 -0700
Message-ID: <CA+renyUW6+JUM5d6OJ8XZR3araY2iii5xTYP5kSUjqgLdY+uSg@mail.gmail.com>
Subject: =?UTF-8?Q?Re=3A_LISTAGG_=C3=A0_la_Oracle_in_PostgreSQL?=
To: Pierre Forstmann <pierre.forstmann@gmail.com>
Cc: "pgsql-general@lists.postgresql.org" <pgsql-general@lists.postgresql.org>
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On Mon, Mar 9, 2026 at 1:21=E2=80=AFPM Pierre Forstmann
<pierre.forstmann@gmail.com> wrote:
>
> Hello,
>
> I can write a LISTAGG aggregate for:
>
> create table emp(deptno numeric, ename text);
>
> SELECT deptno, LISTAGG(ename, ','::text ORDER BY ename) AS employees
> FROM   emp GROUP BY deptno ORDER BY deptno;
>
> I would like to know if is possible to create an aggregate LISTAGG that
> would work like in Oracle:
>
> SELECT deptno,
>         listagg(ename, ',') WITHIN GROUP (ORDER BY ename) AS employees
> FROM emp
> GROUP BY deptno
> ORDER BY deptno;

I don't think you need a custom aggregate here. In Postgres you can say:

select deptno,
      string_agg(ename, ',' ORDER BY ename) AS employees
FROM emp
GROUP BY deptno
ORDER BY deptno;

--=20
Paul              ~{:-)
pj@illuminatedcomputing.com