题解 | #汇总各个部门当前员工的title类型的分配数目#

select
dept_no,
dept_name,
title,
count(title) as count1
from
(select
ds.dept_no,
ds.dept_name,
t0.title
from
(select d.dept_no,t.title
from titles t
left join dept_emp d on t.emp_no = d.emp_no
where t.to_date='9999-01-01')t0
left join departments ds on ds.dept_no = t0.dept_no
)t1
group by dept_no,dept_name,title
order by dept_no asc,title asc