如何用PHP实现CMS系统的用户管理功能

CREATE DATABASE cms;
USE cms;
CREATE TABLE users (
    id INT AUTO_INCREMENT PRIMARY KEY,
    username VARCHAR(255) NOT NULL,
    password VARCHAR(255) NOT NULL,
    email VARCHAR(255) NOT NULL,
    role VARCHAR(255)
);

<form action="register.php" method="POST">
    <input type="text" name="username" placeholder="用户名" required>
    <input type="password" name="password" placeholder="密码" required>
    <input type="email" name="email" placeholder="邮箱" required>
    <button type="submit">注册</button>
</form>

<?php
// 连接数据库
$conn = mysqli_connect("localhost", "root", "", "cms");

// 获取用户提交的数据
$username = $_POST["username"];
$password = $_POST["password"];
$email = $_POST["email"];

// 将用户信息插入到数据表中
$query = "INSERT INTO users (username, password, email) VALUES ('$username', '$password', '$email')";
mysqli_query($conn, $query);

// 注册成功后的操作，例如跳转到登录页面
header("Location: login.php");
?>

<form action="login.php" method="POST">
    <input type="text" name="username" placeholder="用户名" required>
    <input type="password" name="password" placeholder="密码" required>
    <button type="submit">登录</button>
</form>

<?php
// 连接数据库
$conn = mysqli_connect("localhost", "root", "", "cms");

// 获取用户提交的数据
$username = $_POST["username"];
$password = $_POST["password"];

// 查询数据库中是否存在匹配的用户信息
$query = "SELECT * FROM users WHERE username='$username' AND password='$password'";
$result = mysqli_query($conn, $query);

// 如果存在匹配的用户，则登录成功，可以执行相应的操作
if (mysqli_num_rows($result) > 0) {
    // 用户登录成功后的操作，例如跳转到用户个人资料页面
    header("Location: profile.php");
} else {
    // 用户登录失败
    echo "用户名或密码错误";
}
?>

// 连接数据库
$conn = mysqli_connect("localhost", "root", "", "cms");

// 获取用户提交的数据
$username = $_POST["username"];
$role = $_POST["role"];

// 更新用户的权限
$query = "UPDATE users SET role='$role' WHERE username='$username'";
mysqli_query($conn, $query);