CREATE DATABASE test;
use test;
CREATE TABLE employee (
    id int,
    name varchar(100),
    salary int,
    department int,
    PRIMARY KEY (id)
);

INSERT INTO employee (id, name, salary, department)
VALUES (1, 'cdc', 10000, '1'),
(2, 'cdc', 15000, '1'),
(3, 'bdg', 10200, '2'),
(4, 'bfbreb', 10300, '1'),
(5, 'brb', 14000, '3'),
(6, 'tne', 9000, '2'),
(7, 'egtb', 20000, '2'),
(8, 'cabebdc', 11000, '3'),
(9, 'btnt', 10000, '3');

SELECT * FROM employee;

-- 查询每个部门的最高薪资
EXPLAIN SELECT department, MAX(salary) AS max_salary
FROM employee
GROUP BY department;