如何使用两个不同的表获得额外的列和行数？

-- 创建 employees 表
CREATE TABLE employees (
    id INT PRIMARY KEY,
    name VARCHAR(100),
    department_id INT
);

-- 创建 departments 表
CREATE TABLE departments (
    id INT PRIMARY KEY,
    name VARCHAR(100),
    location VARCHAR(100)
);

-- 插入示例数据
INSERT INTO employees (id, name, department_id) VALUES (1, 'Alice', 1);
INSERT INTO employees (id, name, department_id) VALUES (2, 'Bob', 2);
INSERT INTO departments (id, name, location) VALUES (1, 'HR', 'New York');
INSERT INTO departments (id, name, location) VALUES (2, 'Engineering', 'San Francisco');

-- 使用内连接获取员工及其部门信息
SELECT e.name AS employee_name, d.name AS department_name, d.location
FROM employees e
INNER JOIN departments d ON e.department_id = d.id;

-- 使用左连接获取所有员工及其部门信息（即使某些员工没有部门）
SELECT e.name AS employee_name, d.name AS department_name, d.location
FROM employees e
LEFT JOIN departments d ON e.department_id = d.id;