MySQL (8.0以下版本) : SELECT WHERE Multiple column and group by max level

Question

我的数据库中有 2 个 table。

我部门的
1. table 名员工。这个 table 是集中存储的。我无权在此table
中进行管理

emp_id	name	job postion	dept_1	dept_2	dept_3
000010	emp1 name1	Director	CEO	Human resource
000012	emp2 name2	employee	CEO	Human resource
000013	emp2 name2	Director	CEO	Human resource	Recruitment
000014	emp2 name2	employee	CEO	Human resource	Recruitment
000015	emp2 name2	employee	CEO	Human resource	Recruitment
..	..	..	..	..
..	..	..	..	..
000200	emp2 name2	Head Director	CEO

2. 部门table。这是我为展示我的部门而创建的 table。

dept_id	dept_level	dept_name	dept_order
1	1	CEO	1
2	2	Human Resource	2
2	3	Recruitment	3
2	3	Training	4
2	2	Sale	5
2	3	Sale planning	6
2	3	Sale marketing	7

我想知道员工属于哪个部门？

我尝试使用命令：

SELECT *
FROM table1
INNER table2 ON (table2.dept_name = table1.dept_1 OR table2.dept_name = table1.dept_2 OR table2.dept_name = table1.dept_3)

但这不是我想要的答案

我要

emp_id	name	job postion	dept_level	dept_name	dept_order
000010	emp1 name1	Director	2	Human Resource	2
000012	emp2 name2	employee	2	Human Resource	2
000013	emp2 name2	Director	3	Recruitment	3
000200	emp2 name2	Head Director	1	CEO	1

我该怎么办？

P.S。对不起我的英语

Answer 1

WITH cte AS ( SELECT *, MAX(d.dept_level) OVER (PARTITION BY e.emp_id) maxlevel
              FROM employees e
              JOIN department d ON d.dept_name IN (e.dept_1, e.dept_2, e.dept_3) )
SELECT * 
FROM cte 
WHERE dept_level = maxlevel
ORDER BY emp_id

对于 MySQL 5.7 / MariaDB 10.1 使用

SELECT *
FROM employees e
JOIN department d ON d.dept_name IN (e.dept_1, e.dept_2, e.dept_3)
JOIN ( SELECT e.emp_id,
              MAX(d.dept_level) maxlevel
       FROM employees e
       JOIN department d ON d.dept_name IN (e.dept_1, e.dept_2, e.dept_3)
       GROUP BY e.emp_id ) ed USING (emp_id)
WHERE d.dept_level = ed.maxlevel
ORDER BY emp_id

fiddle