php上次登录时间

CREATE TABLE users (
    id INT AUTO_INCREMENT PRIMARY KEY,
    username VARCHAR(50) NOT NULL,
    password VARCHAR(255) NOT NULL,
    last_login TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
);

<?php
// 连接数据库
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "myDB";

$conn = new mysqli($servername, $username, $password, $dbname);

if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}

// 用户登录验证
$username = $_POST['username'];
$password = $_POST['password'];

$sql = "SELECT * FROM users WHERE username = '$username' AND password = '$password'";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    // 更新上次登录时间
    $userId = $result->fetch_assoc()['id'];
    $updateSql = "UPDATE users SET last_login = NOW() WHERE id = $userId";
    $conn->query($updateSql);

    echo "登录成功！上次登录时间: " . $result->fetch_assoc()['last_login'];
} else {
    echo "用户名或密码错误";
}

$conn->close();
?>

$stmt = $conn->prepare("SELECT * FROM users WHERE username = ? AND password = ?");
$stmt->bind_param("ss", $username, $password);
$stmt->execute();
$result = $stmt->get_result();