# 177. Nth Highest Salary

## Description

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 salary from the Employee table. If there is no nth highest salary, 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                   |
+------------------------+


## Solutions

Change the 1 after OFFSET to N-1, but then MySQL will report an error and it is estimated that the operation is not supported. Then we can add a SET N = N-1 in front.

• import pandas as pd

def nth_highest_salary(employee: pd.DataFrame, N: int) -> pd.DataFrame:
unique_salaries = employee.salary.unique()
if len(unique_salaries) < N:
return pd.DataFrame([np.NaN], columns=[f"getNthHighestSalary({N})"])
else:
salary = sorted(unique_salaries, reverse=True)[N - 1]
return pd.DataFrame([salary], columns=[f"getNthHighestSalary({N})"])


• CREATE FUNCTION getNthHighestSalary(N INT) RETURNS INT
BEGIN
DECLARE M INT;
SET M=N-1; # index issue
RETURN (
# Write your MySQL query statement below.
SELECT DISTINCT Salary
FROM Employee
ORDER BY Salary DESC
LIMIT 1
OFFSET M
);
END