Антон Матушкин

SELECT
    m.name,
    m.position,
    COUNT(e.name) AS number_of_subordinates
FROM
    employees as e
    RIGHT JOIN employees as m
    ON e.manager_id = m.id
GROUP BY m.name
WHERE m.is_manager = 1

SELECT 
    e.name as Employee, 
    e.position as Position, 
    m.name as Manager
FROM
    employees as e
    LEFT JOIN employees as m
    ON e.manager_id = m.id