Number of employees under top level manager
CREATE TABLE employees ( id INTEGER PRIMARY KEY, name VARCHAR(255) NOT NULL, managerId INTEGER, FOREIGN KEY (managerId) REFERENCES employees(id) ); INSERT INTO employees(id, name, managerId) VALUES(1, 'Rob', null); INSERT INTO employees(id, name, managerId) VALUES(2, 'Tom', null); INSERT INTO employees(id, name, managerId) VALUES(3, 'Roger', 1); INSERT INTO employees(id, name, managerId) VALUES(4, 'Victor', 3); INSERT INTO employees(id, name, managerId) VALUES(5, 'John', 4); INSERT INTO employees(id, name, managerId) VALUES(6, 'Shawn', 2);