Re: LISTAGG à la Oracle in PostgreSQL

Pierre
The equivalent in PostgreSQL is through:

SELECT deptno,
STRING_AGG(ename, ',' ORDER BY ename) AS employeesFROM empGROUP
BY deptnoORDER BY deptno;

Atte
JRBM

El lun, 9 mar 2026 a las 15:21, Pierre Forstmann (<
pierre(dot)forstmann(at)gmail(dot)com>) escribió:

> 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 failed and IA also failed. Claude says:
>
> It is not possible to exactly replicate listagg(ename, ',') WITHIN GROUP
> (ORDER BY ename) as a custom PostgreSQL aggregate
> because PostgreSQL strictly forbids ungrouped columns as direct
> arguments to ordered-set aggregates.
>
> Do you agree ?
>
>
>
>
>
>
>