[SQL문제풀기] 12세 이하인 여자 환자 목록 출력하기 - NULL 처리

문제

MYSQL, ORACLE 공통 - COALESCE : 여러 대안 값을 처리 가능

SELECT PT_NAME, PT_NO, GEND_CD, AGE, COALESCE(TLNO,'NONE') TLNO
FROM PATIENT
WHERE GEND_CD = 'W' AND AGE <= 12 
ORDER BY 4 DESC, 1;

MYSQL

내가 작성한 정답 - IFNULL

SELECT PT_NAME, PT_NO, GEND_CD, AGE, IFNULL(TLNO,'NONE') TLNO
FROM PATIENT
WHERE GEND_CD = 'W' AND AGE <= 12 
ORDER BY 4 DESC, 1;

ORACLE

내가 작성한 정답 - NVL

SELECT PT_NAME, PT_NO, GEND_CD, AGE, NVL(TLNO,'NONE') TLNO
FROM PATIENT
WHERE GEND_CD = 'W' AND AGE <= 12 
ORDER BY 4 DESC, 1;