多层级sql查询

SELECT
    (
        SELECT
            count(1)
        FROM
            t_app_user
        WHERE
            parent_user_id = t.user_id /*多层级，t.user_id */
    ) AS directCount,
    getSubUserCount (user_id) AS subUserCount,
    (
        SELECT
            count(1)
        FROM
            t_card_inf
        WHERE
            user_id = t.user_id 
        AND STATUS = 0
    ) AS cardNum,
    t.*
FROM
    t_app_user t
ORDER BY
    t.row_crt_ts DESC