Próbáld ki ezt:
SELECT employees.*
FROM employees
LEFT JOIN titles ON titles.emp_no = employees.emp_no
AND titles.from_date = (SELECT MAX(from_date) FROM titles WHERE titles.emp_no = employees.emp_no)
AND titles.to_date = (SELECT MAX(to_date) FROM titles WHERE titles.emp_no = employees.emp_no)
LEFT JOIN salaries ON salaries.emp_no = employees.emp_no
AND salaries.from_date = (SELECT MAX(from_date) FROM salaries WHERE salaries.emp_no = employees.emp_no)
AND salaries.to_date = (SELECT MAX(to_date) FROM salaries WHERE salaries.emp_no = employees.emp_no)
LEFT JOIN dept_emp ON
dept_emp.emp_no = employees.emp_no
AND dept_emp.from_date = (SELECT MAX(from_date) FROM dept_emp WHERE dept_emp.emp_no = employees.emp_no)
AND dept_emp.to_date = (SELECT MAX(to_date) FROM dept_emp WHERE dept_emp.emp_no = employees.emp_no)
LEFT JOIN departments ON dept_emp.dept_no = departments.dept_no;