PHP表单提交与数据库插入故障排除：关键的name属性

<button type="submit" class="submit-btn" value="Register"> Register </button>

if (isset($_POST['submit']) ){
    // 注册逻辑
}

<!-- 注册表单中的提交按钮 -->
<button type="submit" name="register" class="submit-btn" value="Register"> Register </button>

<?php 

//include config file
include "config.php";

//register user
// 检查 'register' 按钮是否被点击
if (isset($_POST['register']) ){
    $name = mysqli_real_escape_string($conn, $_POST['name']);
    $email = mysqli_real_escape_string($conn, $_POST['email']);
    // 注意：MD5已过时，推荐使用 password_hash()
    $password = mysqli_real_escape_string($conn, md5 ($_POST['password']) ); 
    $cpassword = mysqli_real_escape_string($conn, md5 ($_POST['cpassword']) );
    $image = $_FILES['image']['name'];
    $image_size = $_FILES['image']['size'];
    $image_tmp_name = $_FILES['image']['tmp_name'];
    $image_folder = "images/".$image;

    // 检查邮箱是否已存在
    $select = mysqli_query($conn, "SELECT * FROM user WHERE email = '$email'") or die(mysqli_error($conn)); // 密码不应在查询中用于检查用户是否存在

    if(mysqli_num_rows($select) > 0){
        $massage[] = "User already exists";
    }else{
        if($password != $cpassword){
            $massage[] = "Password does not match";
        }elseif($image_size > 5097152){
            $massage[] = "Image size should be less than 5MB";
        }else{
            $insert = mysqli_query($conn, "INSERT INTO user (username, email, userpassword, Image) VALUES ('$name', '$email', '$password', '$image')") or die(mysqli_error($conn));
            if($insert){
                move_uploaded_file($image_tmp_name, $image_folder);
                $massage[] = "Registration successful";
                header("location: home.php"); // 注册成功后重定向
                exit(); // 重定向后应立即终止脚本执行
            }else{
                $massage[] = "Registration failed";
            } 
        }  
    }
}

// 登录逻辑（如果存在，也应有自己的 $_POST 检查）
// if (isset($_POST['login_submit_button_name'])) { ... }

?>

// 注册时
$hashed_password = password_hash($_POST['password'], PASSWORD_DEFAULT);
// 插入数据库

// 登录时
// if (password_verify($_POST['password'], $stored_hashed_password)) {
//     // 密码匹配
// }

// 插入用户
$stmt = $conn->prepare("INSERT INTO user (username, email, userpassword, Image) VALUES (?, ?, ?, ?)");
$stmt->bind_param("ssss", $name, $email, $hashed_password, $image);
if ($stmt->execute()) {
    // 成功
} else {
    // 失败
}
$stmt->close();

// 在顶部启动会话
session_start();

// 存储消息
$_SESSION['message'] = "Registration successful";
header("location: home.php");
exit();

// 在 home.php 或其他页面中显示消息
if (isset($_SESSION['message'])) {
    echo '<div class="message">' . $_SESSION['message'] . '</div>';
    unset($_SESSION['message']); // 显示后清除
}