How to use PHP functions to implement user registration and login?

How to use PHP functions to implement user registration and login?

In web development, user registration and login are very common functions. As a popular server-side scripting language, PHP provides a wealth of functions and tools to help us achieve these functions. In this article, we will learn how to use PHP functions to implement user registration and login functions.

First, we need to create a database to store user information. We can use the MySQL database to create a table named "users" with the following code:

CREATE TABLE users (
    id INT(11) PRIMARY KEY AUTO_INCREMENT,
    username VARCHAR(255) NOT NULL,
    password VARCHAR(255) NOT NULL
);

Next, we will write PHP code to handle user registration and login.

User registration function:

<?php
// 连接到数据库
$conn = mysqli_connect("localhost", "username", "password", "database");

// 检查连接是否成功
if (!$conn) {
    die("连接数据库失败: " . mysqli_connect_error());
}

// 处理用户注册
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    // 获取用户输入的用户名和密码
    $username = $_POST["username"];
    $password = $_POST["password"];

    // 插入用户信息到数据库
    $sql = "INSERT INTO users (username, password) VALUES ('$username', '$password')";
    
    if (mysqli_query($conn, $sql)) {
        echo "用户注册成功！";
    } else {
        echo "用户注册失败： " . mysqli_error($conn);
    }
}

// 关闭数据库连接
mysqli_close($conn);
?>

User login function:

<?php
// 连接到数据库
$conn = mysqli_connect("localhost", "username", "password", "database");

// 检查连接是否成功
if (!$conn) {
    die("连接数据库失败: " . mysqli_connect_error());
}

// 处理用户登录
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    // 获取用户输入的用户名和密码
    $username = $_POST["username"];
    $password = $_POST["password"];

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

    if (mysqli_num_rows($result) > 0) {
        echo "用户登录成功！";
    } else {
        echo "用户名或密码错误！";
    }
}

// 关闭数据库连接
mysqli_close($conn);
?>

Through the above code, we can implement user registration and login functions. When a user submits the registration form, the username and password are inserted into the database. When a user submits a login form, the database is queried to see if a matching username and password exist.

Of course, this is just the basic function implemented. In actual development, we also need to consider some security and user experience issues, such as password encryption and verification, form input verification, login status saving, etc.

I hope this article can be helpful to you when using PHP functions to implement user registration and login functions!

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