[SQL][HackerRank] Top Earners - GROUP BY + ROWNUM ORACLE

https://www.hackerrank.com/challenges/earnings-of-employees/problem?isFullScreen=true

Top Earners | HackerRank

코드설명

GROUP BY + ROWNUM 을 활용합니다.

 

ORACLE 코드

정답코드1입니다.

SELECT *
FROM (
    SELECT MONTHS * SALARY, COUNT(EMPLOYEE_ID)
    FROM EMPLOYEE
    GROUP BY (MONTHS * SALARY)
    ORDER BY MONTHS * SALARY DESC
    )
WHERE ROWNUM = 1;

 

오답코드1입니다. MAX 함수의 MAX_SALARY를 쿼리에 사용하려고 했지만, not a single-group group function 에러가 발생합니다. 

SELECT  MAX(MONTHS * SALARY), 
    ( SELECT COUNT(EMPLOYEE_ID) FROM EMPLOYEE WHERE MONTHS*SALARY = (SELECT MAX(MONTHS * SALARY) FROM EMPLOYEE) )
FROM EMPLOYEE;