Employees Whose Manager Left the Company — LeetCode 1978 Python Solution

Table: Employees +-------------+----------+ | Column Name | Type | +-------------+----------+ | employee_id | int | | name | varchar | | manager_id | int | | salary | int | +-------------+----------+ In SQL, employee_id is the primary key for this table. This table contains information about the employees, their salary, and the ID of their manager.

+-------------+----------+
| Column Name | Type     |
+-------------+----------+
| employee_id | int      |
| name        | varchar  |
| manager_id  | int      |
| salary      | int      |
+-------------+----------+
In SQL, employee_id is the primary key for this table.
This table contains information about the employees, their salary, and the ID of their manager. Some employees do not have a manager (manager_id is null).

import duckdb
import pandas as pd

def solution(employees: pd.DataFrame) -> pd.DataFrame:
    con = duckdb.connect()
    con.register("Employees", employees)
    return con.execute("""SELECT e1.employee_id
FROM
    Employees AS e1
    LEFT JOIN Employees AS e2 ON e1.manager_id = e2.employee_id
WHERE e1.salary < 30000 AND e1.manager_id IS NOT NULL AND e2.employee_id IS NULL
ORDER BY 1;""").df()