> On 26 Jul 2021, at 17:52, Alban Hertroys <haramrae@xxxxxxxxx> wrote: > Something like this: > > with recursive foo (id, parent, children_ids) as ( > select id, parent, null::text > from tree t > where not exists ( > select 1 from tree c where c.parent = t.id > ) > union all > select t.id, t.parent > , f.id || case f.children_ids when '' then '' else ',’ end || f.children_ids > from foo f > join tree t on f.parent = t.id > where f.parent <> 0 > ; Almost, the null::text in the initial select should of course be '’ in your case, and a unicode quote slipped into the last string of that case statement. Alban Hertroys -- If you can't see the forest for the trees, cut the trees and you'll find there is no forest.
