문제 link
https://www.hackerrank.com/challenges/earnings-of-employees/problem
Code link
https://github.com/JamesJung01/Hackerrank_sql/blob/main/01_Easy/Top_Earners.sql
SELECT (SALARY*MONTHS), COUNT(SALARY*MONTHS) FROM EMPLOYEE GROUP BY (SALARY*MONTHS) ORDER BY (SALARY*MONTHS) DESC LIMIT 1;