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19.查找所有员工的last_name和first_name以及对应的dept_name.md 936 Bytes
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xuthus authored 2019-08-13 08:38 . revise:content revision

查找所有员工的last_name和first_name以及对应的dept_name

题目描述

查找所有员工的last_name和first_name以及对应的dept_name,也包括暂时没有分配部门的员工

CREATE TABLE `departments` (
`dept_no` char(4) NOT NULL,
`dept_name` varchar(40) NOT NULL,
PRIMARY KEY (`dept_no`));
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 `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`));

答案

select e.last_name,e.first_name,d.dept_name from employees e left join dept_emp de on e.emp_no = de.emp_no left join departments d on de.dept_no = d.dept_no

题解

三表连接

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