[HackerRank SQL] New Companies

문제 link
https://www.hackerrank.com/challenges/the-company/problem

Code link
https://github.com/JamesJung01/Hackerrank_sql/blob/main/02_Medium/New_Companies.sql

SELECT C.COMPANY_CODE, 
       C.FOUNDER, 
       COUNT(DISTINCT L.LEAD_MANAGER_CODE), 
       COUNT(DISTINCT S.SENIOR_MANAGER_CODE),
       COUNT(DISTINCT M.MANAGER_CODE),
       COUNT(DISTINCT E.EMPLOYEE_CODE)
FROM COMPANY AS C,
     LEAD_MANAGER AS L,
     SENIOR_MANAGER AS S,
     MANAGER AS M,
     EMPLOYEE AS E
WHERE C.COMPANY_CODE = L.COMPANY_CODE
AND L.LEAD_MANAGER_CODE = S.LEAD_MANAGER_CODE
AND S.SENIOR_MANAGER_CODE = M.SENIOR_MANAGER_CODE
AND M.SENIOR_MANAGER_CODE = E.MANAGER_CODE
GROUP BY C.COMPANY_CODE, C.FOUNDER
ORDER BY C.COMPANY_CODE;