MySQL Solution
SELECT e.employee_id\nFROM Employees e\nWHERE e.employee_id NOT IN (SELECT s.employee_id FROM Salaries s)\n\nUNION\n\nSELECT s.employee_id\nFROM Salaries s\nWHE
SELECT e.employee_id\nFROM Employees e\nWHERE e.employee_id NOT IN (SELECT s.employee_id FROM Salaries s)\n\nUNION\n\nSELECT s.employee_id\nFROM Salaries s\nWHERE s.employee_id NOT IN (SELECT e.employee_id FROM Employees e)\n\nORDER BY employee_id;
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