-- https://leetcode.com/problems/employees-earning-more-than-their-managers/submissions/986199313/
select e.name as employee
from employee e, employee ee
where e.managerid= ee.id and e.salary> ee.salary
JOIN 하는 게 더 느릴 것 같았는데 더 빠른가봄?
select e1.name as Employee
from Employee e1
left join Employee e2
on e1.managerId = e2.id
where e1.salary > e2.salary
select email
from person
group by email
having count(*)>1