If your getting EROOR CODE 1055: Try This Code Instead!

SELECT 
    m.dept_no, m.emp_no, d.dept_name
FROM
    dept_manager_dup m
        JOIN
    department_dup d ON m.dept_no = d.dept_no
GROUP BY m.dept_no, m.emp_no, d.dept_name
ORDER BY m.dept_no;