Problem

Write a SQL query to get the nth highest salary from the Employee table.

For example, given the above Employee table, the nth highest salary where n = 2 is 200. If there is no nth highest salary, then the query should return null.

Solution

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