Nth highest salary

--
-- Table: Employee
-- +-------------+------+
-- | Column Name | Type |
-- +-------------+------+
-- | id          | int  |
-- | salary      | int  |
-- +-------------+------+
-- id is the primary key (column with unique values) for this table.
-- Each row of this table contains information about the salary of an employee.
-- Write a solution to find the nth highest distinct salary from the Employee table. If there are less than n distinct salaries, return null.
-- The result format is in the following example.
-- Example 1:
-- Input:
-- Employee table:
-- +----+--------+
-- | id | salary |
-- +----+--------+
-- | 1  | 100    |
-- | 2  | 200    |
-- | 3  | 300    |
-- +----+--------+
-- n = 2
-- Output:
-- +------------------------+
-- | getNthHighestSalary(2) |
-- +------------------------+
-- | 200                    |
-- +------------------------+
-- Example 2:
-- Input:
-- Employee table:
-- +----+--------+
-- | id | salary |
-- +----+--------+
-- | 1  | 100    |
-- +----+--------+
-- n = 2
-- Output:
-- +------------------------+
-- | getNthHighestSalary(2) |
-- +------------------------+
-- | null                   |
-- +------------------------+

CREATE FUNCTION getNthHighestSalary(N INT) RETURNS INT
BEGIN
  SET N = N - 1;
  RETURN (
    SELECT DISTINCT salary
    FROM Employee
    ORDER BY salary DESC
    LIMIT 1 OFFSET N
  );
END