數據庫SQL實戰（牛客網）：獲取所有部門當前manager的當前薪水情況

獲取所有部門當前manager的當前薪水情況，給出dept_no, emp_no以及salary，當前表示to_date=‘9999-01-01’
CREATE TABLE dept_manager (
dept_no char(4) NOT NULL,
emp_no int(11) NOT NULL,
from_date date NOT NULL,
to_date date NOT NULL,
PRIMARY KEY (emp_no,dept_no));
CREATE TABLE salaries (
emp_no int(11) NOT NULL,
salary int(11) NOT NULL,
from_date date NOT NULL,
to_date date NOT NULL,
PRIMARY KEY (emp_no,from_date));

select a.dept_no , b.emp_no , b.salary 
from dept_manager as a join salaries as b
on a.emp_no = b.emp_no
where a.to_date='9999-01-01' and b.to_date='9999-01-01';