如何使用select语句中的一列的值来显示连接中的列？

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

CREATE TABLE departments (
    id INT PRIMARY KEY,
    name 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) VALUES (1, 'HR');
INSERT INTO departments (id, name) VALUES (2, 'Engineering');

-- 使用内连接显示员工及其部门名称
SELECT employees.name AS employee_name, departments.name AS department_name
FROM employees
INNER JOIN departments ON employees.department_id = departments.id;

-- 使用左连接确保所有员工都显示，即使他们没有对应的部门
SELECT employees.name AS employee_name, departments.name AS department_name
FROM employees
LEFT JOIN departments ON employees.department_id = departments.id;