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 d.dept_no, dept_name, count(*) sum from departments d join dept_emp de on d.dept_no = de.dept_no left join salaries s on de.emp_no = s.emp_no group by d.dept_no order by d.dept_no