select emp_no, birth_date, first_name, last_name, gender, hire_date
from (select *, 
      dense_rank() over(order by hire_date desc) as rk
      from employees) as t1
where rk = 3

假设有一组数：60,59,57,57,55不同的函数排序结果：

dense_rank() 1 2 3 3 4

rank() 1 2 3 3 5

row_number() 1 2 3 4 5