코딩테스트 연습 > SELECT > 12세 이하인 여자 환자 목록 출력하기
https://school.programmers.co.kr/learn/courses/30/lessons/132201

SELECT pt_name, pt_no, gend_cd, age, ifnull(tlno, "NONE") as tlno
from patient
where age <= 12 and gend_cd = 'W'
order by age desc, pt_name asc