【数据库SQL实战】查找当前薪水详情以及部门编号dept_no

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查找各个部门当前(to_date=’9999-01-01’)领导当前薪水详情以及其对应部门编号dept_no
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));

两种解法本质上都是连接两个表。

解法一：

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

解法二:

SELECT s.*, d.dept_no 
FROM salaries s ,  dept_manager d
WHERE s.to_date='9999-01-01'
AND d.to_date='9999-01-01'
AND s.emp_no = d.emp_no;