题解 | #统计各个部门的工资记录数#

# 用窗口函数统计出记录数sum,然后再用distinct去重

select distinct dept_no,dept_name,sum
from
(
select d.dept_no,d.dept_name,count(s.salary) over (partition by d.dept_no) as sum
from departments d
    left join dept_emp de on d.dept_no = de.dept_no
    left join salaries s on de.emp_no = s.emp_no
order by d.dept_no
) as a