题解 | 汇总各个部门当前员工的title类型的分配数目

SELECT d2.dept_no, dept_name,t.title, count(*) as count
FROM dept_emp d
LEFT JOIN titles t on d.emp_no = t.emp_no
LEFT JOIN departments d2 on d.dept_no = d2.dept_no
GROUP BY d2.dept_no,dept_name, t.title
ORDER BY d2.dept_no asc, t.title asc