題目描述:查找各個部門當前(to_date='9999-01-01')領導當前薪水詳情以及其對應部門編號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`));
思路:salaries是主表,dept_manager是從表
注:from後的順序不能錯
題解:
select s.emp_no,s.salary,s.from_date,s.to_date,dm.dept_no from
salaries s,dept_manager dm where
s.to_date='9999-01-01' AND
dm.to_date='9999-01-01'AND
dm.emp_no = s.emp_no;