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  • mysql内连接的复杂应用

    查找所有员工自入职以来的薪水涨幅情况,给出员工编号emp_noy以及其对应的薪水涨幅growth,并按照growth进行升序
    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`));

    用内连接实现:

    select a.emp_no, (b.salary - c.salary) as growth
    from
        employees as a
        inner join salaries as b
        on a.emp_no = b.emp_no and b.to_date = '9999-01-01'
        inner join salaries as c
        on a.emp_no = c.emp_no and a.hire_date = c.from_date
    order by growth asc

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  • 原文地址:https://www.cnblogs.com/chohyee/p/7384075.html
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