✅✅Easy || By Union || Order BY || NOT IN
\n(\n    SELECT e2.employee_id FROM salaries AS e2 \nWHERE e2.employee_id NOT IN (SELECT Employees.employee_id FROM Employees)\nUNION\nSELECT e1.employee_id FRO
```\n(\n    SELECT e2.employee_id FROM salaries AS e2 \nWHERE e2.employee_id NOT IN (SELECT Employees.employee_id FROM Employees)\nUNION\nSELECT e1.employee_id FROM Employees e1 WHERE\ne1.employee_id NOT IN (SELECT Salaries.employee_id FROM Salaries)\n) ORDER BY employee_id\n# atlast order by employee_id\n```
['Union Find', 'MySQL', 'Oracle']