REGEXP_REPLACE

SELECT 휴대폰번호, SUBSTR(휴대폰번호, 1, 4) || REGEXP_REPLACE(SUBSTR(휴대폰번호, 5), '[[:digit:]]', '*') 변경칼럼
FROM(
    SELECT '010-123-1234' 휴대폰번호 FROM DUAL
    UNION ALL
    SELECT '010-1234-1234' 휴대폰번호 FROM DUAL);