Re: LISTAGG à la Oracle in PostgreSQL

On Mon, Mar 9, 2026 at 1:21 PM Pierre Forstmann
<pierre(dot)forstmann(at)gmail(dot)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;

--
Paul ~{:-)
pj(at)illuminatedcomputing(dot)com