오라클 SQL 상위 하위 10% 뽑아내기

WITH temp AS (
SELECT LEVEL AS grd
, COUNT(*) OVER() * 0.1 AS rate
, RANK() OVER (ORDER BY LEVEL DESC) AS f_rnk
, RANK() OVER (ORDER BY LEVEL ASC) AS l_rnk
FROM dual
connect BY LEVEL < 101
)
SELECT grd, rate, f_rnk, l_rnk
FROM temp
WHERE f_rnk <= rate
OR l_rnk <= rate