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 dept_no, dept_name, count(salary) as sum from departments right join dept_emp using(dept_no) right join salaries using(emp_no) group by dept_no order by dept_no