牛客 SQL：统计各个部门的工资记录数

题目：统计各个部门的工资记录数

代码：

SELECT dp.dept_no, dp.dept_name, T.MYSUM
FROM departments AS dp
INNER JOIN 
(
    SELECT de.dept_no, COUNT(*) AS MYSUM
    FROM dept_emp AS de
    INNER JOIN salaries AS s
    ON de.emp_no = s.emp_no
    GROUP BY de.dept_no
) AS T

ON dp.dept_no = T.dept_no
ORDER BY dp.dept_no ASC