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
http://www.nowcoder.com/practice/6a62b6c0a7324350a6d9959fa7c21db3
SELECT
t.dept_no,
d.dept_name,
t.sum
FROM
(
SELECT
s.emp_no,
count( s.salary ) AS sum,
dp.dept_no
FROM
salaries AS s
INNER JOIN dept_emp AS dp ON s.emp_no = dp.emp_no
GROUP BY
dp.dept_no
) AS t
INNER JOIN departments AS d ON t.dept_no = d.dept_no
ORDER BY
t.dept_no; 
