MS SQL | SIMPLE | 2 APPROACH
Using UNION ALL\n\nSELECT employee_id\nFROM (\n        SELECT E.employee_id\n        FROM Employees E\n        LEFT JOIN Salaries S ON S.employee_id = E.employe
1. Using **UNION ALL**\n```\nSELECT employee_id\nFROM (\n        SELECT E.employee_id\n        FROM Employees E\n        LEFT JOIN Salaries S ON S.employee_id = E.employee_id\n        WHERE name IS NULL OR salary IS NULL\n\n        UNION ALL\n\n        SELECT S.employee_id\n        FROM Employees E\n        RIGHT JOIN Salaries S ON S.employee_id = E.employee_id\n        WHERE name IS NULL OR salary IS NULL\n)A\nORDER BY 1 \n```\n\n2. Using **FULL OUTER JOIN** \n```\nSELECT ISNULL(E.employee_id, S.employee_id) employee_id\nFROM Employees E\nFULL OUTER JOIN Salaries S ON S.employee_id = E.employee_id\nWHERE E.employee_id IS NULL OR S.employee_id IS NULL\nORDER BY 1 ASC\n```
['Union Find', 'MS SQL Server']