https://docs.oracle.com/en/database/oracle/oracle-database/21/sqlrf/Hierarchical-Queries.html
https://docs.oracle.com/cd/B19306_01/server.102/b14200/queries003.htm
https://docs.oracle.com/database/121/SQLRF/queries003.htm#SQLRF52332
일반적 상황에서는 다음 쿼리를 바탕으로 사용할 수 있다.
SELECT last_name, employee_id, manager_id, LEVEL
FROM employees
START WITH employee_id = 100
CONNECT BY PRIOR employee_id = manager_id
ORDER SIBLINGS BY last_name;