题解 | #统计各个部门的工资记录数#
统计各个部门的工资记录数
https://www.nowcoder.com/practice/6a62b6c0a7324350a6d9959fa7c21db3
select a.dept_no,a.dept_name,count(c.salary) sum from
departments a
join dept_emp b on a.dept_no = b.dept_no
join salaries c on b.emp_no = c.emp_no
-- group by 后可跟多个筛选条件，这里严格上应该时两个限定条件，前面才能查得到(a.dept_no,a.dept_name)
group by a.dept_no,a.dept_name
order by a.dept_no asc
