题解 | #汇总各个部门当前员工的title类型的分配数目#

SELECT B.dept_no,B.dept_name,C.title,COUNT(*) AS 'COUNT'
    FROM dept_emp A LEFT JOIN departments B
    ON A.dept_no = B.dept_no AND A.to_date = '9999-01-01'
    JOIN titles C
    ON A.emp_no = C.emp_no AND A.to_date = '9999-01-01'
    GROUP BY dept_no,title
    ORDER BY dept_no