https://leetcode.com/problems/project-employees-i/description/
MySQL, Oracle
SELECT a.project_id, ROUND(SUM(b.experience_years) / COUNT(b.experience_years), 2) as average_years
FROM Project a JOIN Employee b ON a.employee_id = b.employee_id
GROUP BY a.project_id간단한 평균을 구하는 문제
간단해서 MySQL 이든 Oracle 이든 동일한 풀이다.
속도도 그럭저럭
