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