해커랭크(HackerRank) MySQL-Top Earners

SELECT *
FROM (
    select salary*months as earning,
           count(salary*months) as counting
    from Employee
    GROUP BY earning
    ) as salary
order by earning desc
limit 1

 

처음엔 이렇게 풀었다. 답은 나오지만 더 효율적인 코드는

 

select salary*months as earning, count(salary*months)
from Employee
where salary*months=(select max(salary*months) from Employee)
group by earning

select salary*months as earning, count(salary*months)
from Employee
group by earning
having earning=(select max(salary*months) from Employee)

 

✅ 예약어(SELECT, AND) 등은 대문자로 쓰는 습관을 가지자