DECODE, SUBSTR, TO_CHAR

SELECT empno
           , jumin_no
           , emp_name
           , birth_date
           , birth_code
FROM LKDM_A01
ORDER BY jumin_no

/*
 생일 코드가 1이면 음력, 2이면 양력이 되도록 하자
*/
SELECT empno
           , jumin_no
           , emp_name
           , birth_date
           , DECODE(birth_code,'2','음력','양력') 구분
FROM LKDM_A01
ORDER BY jumin_no

/*
 주민등록번호 '-''로 쪼개기
*/
SELECT empno
           , SUBSTR(JUMIN_NO,1,6) || '-' || SUBSTR(JUMIN_NO,7) JUMIN_NO
           , emp_name
           , birth_date
           , DECODE(birth_code,'2','음력','양력') 구분
FROM LKDM_A01
ORDER BY jumin_no

/*
 날짜 형식 바꾸기
*/
SELECT empno 사원번호
           , SUBSTR(JUMIN_NO,1,6) || '-' || SUBSTR(JUMIN_NO,7) 주민등록번호
           , emp_name 성명
           , TO_CHAR(BIRTH_DATE, 'YYYY-MM-DD') 생일
           , DECODE(birth_code,'2','음력','양력') 구분
FROM LKDM_A01
ORDER BY jumin_no