[MySQL]조건에 맞는 회원수 구하기

https://school.programmers.co.kr/learn/courses/30/lessons/131535

SELECT COUNT(*) AS USERS
FROM USER_INFO
WHERE JOINED LIKE '2021%'
    AND 20<=AGE AND AGE<=29;

SELECT COUNT(*) AS USERS
FROM USER_INFO
WHERE JOINED LIKE '2021%'
    AND AGE BETWEEN 20 AND 29;

• between보다는 부등호 사용하는 것이 더 성능이 좋다고 한다..!
• 부등호 이렇게 하면 안된다..

SELECT COUNT(*) AS USERS
FROM USER_INFO
WHERE JOINED LIKE '2021%'
    AND 20<=AGE<=29;