[leetcode][DataBase] - 177. Nth Highest Salary with [MySQL]

      # 184ms
      select min(aa.Salary) from 
      (select distinct Salary from employee order by Salary desc limit N) as aa
      where
      (select count(distinct Salary) from employee) >= N

      # 188ms       
      select aa.Salary as ass from 
      (select distinct Salary from employee order by Salary desc limit N) as aa
      where
      (select count(distinct Salary) from employee) >= N
      order by ass
      limit 1