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(*) from dept_emp de
INNER join departments d on de.dept_no=d.dept_no and de.to_date='9999-01-01'
inner join titles t on t.emp_no=de.emp_no
group by d.dept_no,d.dept_name,t.title
ORDER by d.dept_no