题解 | #统计各个部门的工资记录数#

select dept_no, dept_name, 
    count(salary)
FROM dept_emp
join salaries using(emp_no)
join departments using(dept_no)
group by dept_no
order by dept_no

窗口函数

select distinct dept_no, dept_name, 
    count(salary) over(partition by dept_no order by dept_no)
FROM dept_emp
join salaries using(emp_no)
join departments using(dept_no)