WITH t AS
(
SELECT '1' v FROM dual
UNION ALL SELECT '23' FROM dual
UNION ALL SELECT '78' FROM dual
UNION ALL SELECT '54' FROM dual
UNION ALL SELECT '12345678' FROM dual
)
SELECT v
     , TRANSLATE(TRANSLATE('12345678', v, 'YYYYYYYY'), '12345678', 'NNNNNNNN') r
     , REGEXP_REPLACE(TRANSLATE('12345678', v, 'YYYYYYYY'), '[^Y]', 'N') r
FROM t
;

쌩유베리 감사~~~

찾던 기능이였어요.. ㅋ