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
考点：count/join
select d.dept_no, d.dept_name, count(s.emp_no)
from dept_emp de, departments d, salaries s
where de.dept_no = d.dept_no and
de.emp_no = s.emp_no
group by d.dept_no
