Oracle SQL - opret streng ved at sammenkæde rækker, men overstiger ikke X antal tegn

Jeg prøvede følgende forespørgsel og opnåede det ønskede resultat.

SELECT
    LISTAGG(X, ',') WITHIN GROUP(
        ORDER BY
            X
    ) as result
FROM
    (
        SELECT
            X,
            SUM(LENGTH(X)) OVER(
            ORDER BY
                X
            ) LENGTH_X,
            COUNT(1) OVER(
            ORDER BY
                X
            ) - 1 AS COMMAS
        FROM
            (
                SELECT
                    LEVEL   X
                FROM
                    DUAL
                CONNECT BY
                    LEVEL <= 20
            )
    )
GROUP BY
    CEIL((LENGTH_X + COMMAS) / 15);

Output:

db<>fiddle-demo

Skål!!