https://hmjkor.tistory.com/450
이거때문에 갈굼당함..
-- https://leetcode.com/problems/employee-bonus/description/
select e.name, b.bonus
from employee e
left outer join bonus b
on e.empid=b.empid
where b.bonus<1000 or b.bonus is null
left outer join
해서 1000미만인 것만 뽑으면 null인 게 같이 출력이 안된다.. 원래 안됐었나ㅏ..?