Simplest solution using NOT IN & UNION in Postgres 🔥
Code


# Code
```postgresql []
-- Write your PostgreSQL query statement below
select employee_id from employees where employee_id not in (select employee_id from salaries)
union 
select employee_id from salaries where employee_id not in (select employee_id from 
employees)
order by employee_id asc;
```
['PostgreSQL']