题解 | 汇总各个部门当前员工的title类型的分配数目

SELECT 
    d.dept_no,
    d.dept_name,
    t.title,
    COUNT(t.title) AS count
FROM
    dept_emp de 
    LEFT JOIN departments d ON de.dept_no = d.dept_no
    RIGHT JOIN titles t ON de.emp_no = t.emp_no
GROUP BY
    d.dept_no,
    d.dept_name,
    t.title
ORDER BY
    d.dept_no ASC,
    t.title ASC;