勿忘on条件，按emp_no排序

感觉这题目描述的不准确，看了讨论区才理解对。。
连接表达式写法

select s.*,d.dept_no
from salaries as s  inner join dept_manager as d
on s.emp_no=d.emp_no
where s.to_date='9999-01-01' and d.to_date='9999-01-01'

或者

select s.*,d.dept_no
from salaries as s , dept_manager as d
on s.emp_no=d.emp_no
where s.to_date='9999-01-01' and d.to_date='9999-01-01'