SQL | Easy INNER JOIN & UNION
\nSELECT employee_id FROM employees\nWHERE employee_id NOT IN (SELECT employee_id FROM salaries)\nUNION\nSELECT employee_id FROM salaries\nWHERE employee_id NOT
```\nSELECT employee_id FROM employees\nWHERE employee_id NOT IN (SELECT employee_id FROM salaries)\nUNION\nSELECT employee_id FROM salaries\nWHERE employee_id NOT IN (SELECT employee_id FROM employees)\nORDER BY employee_id;\n\n```
['Union Find', 'MySQL']