SQL11

 题目描述
获取所有非manager员工当前的薪水情况，给出dept_no、emp_no以及salary ，当前表示to_date='9999-01-01'

    CREATE TABLE `dept_emp` (
    `emp_no` int(11) NOT NULL,
    `dept_no` char(4) NOT NULL,
    `from_date` date NOT NULL,
    `to_date` date NOT NULL,
    PRIMARY KEY (`emp_no`,`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 `employees` (
    `emp_no` int(11) NOT NULL,
    `birth_date` date NOT NULL,
    `first_name` varchar(14) NOT NULL,
    `last_name` varchar(16) NOT NULL,
    `gender` char(1) NOT NULL,
    `hire_date` date NOT NULL,
    PRIMARY KEY (`emp_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`));

示例：
dept_no    | emp_no|salary

d001    |10001  | 88958

d004    |10003  | 43311

解答思路：
先查出所有员工的工资情况，再排除掉非manager员工的记录

        1.select salary from salaries s left join dept_emp de on s.emp_no=de.emp_no where 
    s.to_date='9999-01-01'

    
        2.select de.dept_no,de.emp_no from dept_emp de left join dept_manager dr on 
    de.emp_no=dr.emp_no  where de.to_date='9999-01-01' and dr.emp_no is null

故答案为：

    select de.dept_no,de.emp_no,
    (select salary from salaries where 
     emp_no=de.emp_no and to_date='9999-01-01') as salary 
    from dept_emp de left join dept_manager dm 
    on de.emp_no=dm.emp_no  where de.to_date='9999-01-01' and dm.emp_no is null;