ROWNUM vs DENSE_RANK

SELECT 
    name, 
    salary,
    ROW_NUMBER() OVER (ORDER BY salary DESC) as row_num,
    DENSE_RANK() OVER (ORDER BY salary DESC) as dense_rank
FROM Employee
ORDER BY salary DESC;

-- 결과:
-- Name   | Salary | ROW_NUMBER | DENSE_RANK
-- -------|--------|------------|------------
-- 김철수  | 10000  |     1      |     1
-- 이영희  | 9000   |     2      |     2
-- 박민수  | 9000   |     3      |     2     ← 같은 순위!
-- 최지훈  | 8000   |     4      |     3     ← 다음 순위는 3
-- 홍길동  | 7000   |     5      |     4