[SQL문제풀기] 멘토링 짝꿍 리스트

문제

solvesql.com

https://solvesql.com/problems/mentor-mentee-list/

SQLite

내가 작성한 정답

select e.employee_id mentee_id, e.name mentee_name, 
       r.employee_id mentor_id, r.name mentor_name
from employees e
left join employees r 
      on e.department <> r.department
      and date(r.join_date) <= '2019-12-31'
where date(e.join_date) between '2021-10-01' and '2021-12-31'
order by mentee_id, mentor_id