postgresql - trouble to order a list obtained by string_agg

I obtained a list of numbers (and text) by a string_agg. For instance, that : "09,12,20,200,217,400,500,90,91,92,Exp3" This is the string_agg: string_agg(DISTINCT t_ligne.ligne_code::text, ','::text ORDER BY (t_ligne.ligne_code::text)) AS lignes My trouble with the ordering: I need an alphanumeric order like: "09,12,20,90,91,92,200,217,400,500,Exp3" If I try a CAST, it refuses to accept text "numbers" like "Exp3". So I didn't find any way to order it like values with text objects at the end. EDIT I don't know how to use WITH in my query without cutting my results! In fact, this is the total query: SELECT l_arret_ligne.idap, t_arret.nom_arret AS nom, string_agg(DISTINCT t_ligne.ligne_code::text, ','::text ORDER BY (t_ligne.ligne_code::text)) AS lignes FROM l_arret_ligne, t_ligne, t_arret WHERE l_arret_ligne.id_ligne::text = t_ligne.id_ligne::text AND l_arret_ligne.idap::text = t_arret.idap::text AND t_ligne.ligne_type::text 'Scolaire'::text GROUP BY l_arret_ligne.idap, t_arret.nom_arret As my string_agg is inside a global query, I don't understand how it would be possible to cut it with WITH and globalize it at the end. Maybe do I understand bad... Thanks again! EDIT 2: Hello again! I found one very good solution to order my results: SELECT string_agg("rla"."t_ligne_19032019"."ligne_code", ',' ORDER BY case when (UPPER(ligne_code)=LOWER(ligne_code))=true then substring(concat('000000000000000',ligne_code),length(ligne_code)+1,15) else ligne_code end) AS lignes FROM "rla"."t_ligne_19032019" It works very well. BUT always the same trouble with DISTINCT! If I add DISTINCT in the string_agg, same message: > ERROR: in an aggregate with DISTINCT, ORDER BY expressions must > appear in argument list Any solution? Any advice? Thanks again! Cyril