SELECT
    SUM(SUMME.UNBEARBEITET) AS UNBEARBEITET,
    SUM(SUMME.GESAMT) AS GESAMT
FROM (
        SELECT
            COUNT(*) AS UNBEARBEITET,
            0        AS GESAMT
        FROM
            IM_POSTEINGANG P1
        WHERE
            P1.SACHBEARBEITER_PK = 1
        AND P1.PROCESSED_DATE IS NOT NULL
        UNION
        SELECT
            0        AS UNBEARBEITET,
            COUNT(*) AS GESAMT
        FROM
            IM_POSTEINGANG P2
        WHERE
            P2.SACHBEARBEITER_PK = 1
) AS SUMME