Oracle SQL - Genera righe aggregate per determinate righe utilizzando select

Un approccio potrebbe essere quello di utilizzare un'unione:

WITH cte AS (
    SELECT "FILE", ID, PARENTID, SHOWCHILD, CAT1, CAT2, CAT3, TOTAL, 1 AS position
    FROM yourTable
    UNION ALL
    SELECT 'Tot', 'Res', 'Res', 'N', SUM(CAT1), SUM(CAT2), SUM(CAT3), SUM(TOTAL), 2
    FROM yourTable
    WHERE SHOWCHILD = 'Y'
)

SELECT "FILE", ID, PARENTID, SHOWCHILD, CAT1, CAT2, CAT3, TOTAL
FROM cte
ORDER BY
    position,
    "FILE";

Dimostrazione