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,ds.dept_name,t.title,count(*) count
from dept_emp d left join titles t on d.emp_no=t.emp_no
    left join departments ds on d.dept_no=ds.dept_no
WHERE d.to_date='9999-01-01' and t.to_date='9999-01-01'
group by d.dept_no,ds.dept_name,t.title
order by d.dept_no,t.title