Get the Employees Managed by a Single Manager

SELECT e.emp_id , e.first_name , e.last_name FROM employees e INNER JOIN managers m ON m.mgr_id = e.mgr_id WHERE m.mgr_id = 'M01' ;

Results in:

EMP_ID | FIRST_NAME | LAST_NAME | — | — | — | E02 | Erin | Macklemore | E04 | Ron | Sonswan |

Ultimately, for every manager we query for, we will see 1 or more employees returned.