오라클 펑션 - 문자형숫자인지 확인

CREATE OR REPLACE FUNCTION IS_NUMBER
(
        V_STR_NUMBER    IN VARCHAR2
)       RETURN          VARCHAR2
IS
        V_NUM           NUMBER;
BEGIN
        V_NUM := TO_NUMBER(REPLACE(TRANSLATE(TO_SINGLE_BYTE(V_STR_NUMBER), '-~', '  '), ' '));
        RETURN 'Y';
        EXCEPTION
        WHEN OTHERS THEN
                RETURN 'N';
END;