Two tables or Three tables?

It seems that three tables were used in the video: employees, dept_manager and dept_emp.
Both dept_manager and dept_emp has same column names.
In my query I used employees and dept_emp tables
(SELECT
                    emp_no
                FROM
                  dept_emp de        <--- Here I didn't used dept_manager
                WHERE
                    emp_no = 110022) AS manager_ID