题解 | #汇总各个部门当前员工的title类型的分配数目#

主要考察group by多重分组,

    select ds.dept_no,ds.dept_name,dept.title,dept.count
from departments as ds join
    (
    select de.dept_no,t.title,count(t.title) as count
    from titles as t join dept_emp as de
    on t.emp_no=de.emp_no
    group by de.dept_no,t.title
    order by t.title
    ) as dept
 on ds.dept_no = dept.dept_no
 order by ds.dept_no asc

内查询中需要加个排序 不然答案一样 顺序不同 牛客编译还是会报错