-- Suggested testing environment:
-- http://sqlite.online/

-- Example case create statement:
CREATE TABLE employees (
  id INTEGER NOT NULL PRIMARY KEY,
  managerId INTEGER REFERENCES employees(id), 
  name VARCHAR(30) NOT NULL
);

INSERT INTO employees(id, managerId, name) VALUES(1, NULL, 'John');
INSERT INTO employees(id, managerId, name) VALUES(2, 1, 'Mike');

-- Expected output (in any order):
-- name
-- ----
-- Mike

-- Explanation:
-- In this example.
-- John is Mike's manager. Mike does not manage anyone.
-- Mike is the only employee who does not manage anyone.