mysql, left join / right join / union
There is no outer join in MySQL.\nhttps://leetcode.com/submissions/detail/857838266/\n\n# Write your MySQL query statement below\n(\n    select e.employee_id \n
There is no `outer join` in MySQL.\nhttps://leetcode.com/submissions/detail/857838266/\n```\n# Write your MySQL query statement below\n(\n    select e.employee_id \n    from Employees as e\n    left join Salaries as s\n    on e.employee_id = s.employee_id\n    where s.employee_id is null\n)\nunion\n(\n    select s.employee_id\n    from Employees as e\n    right join Salaries as s\n    on e.employee_id = s.employee_id\n    where e.employee_id is null\n)\norder by employee_id\n```
['Union Find', 'MySQL']