mysqli登录代码

<?php
// 数据库连接信息
$servername = "localhost";
$username = "your_username";
$password = "your_password";
$dbname = "your_database";

// 创建连接
$conn = new mysqli($servername, $username, $password, $dbname);

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

// 预处理语句
$stmt = $conn->prepare("SELECT id FROM users WHERE username = ? AND password = ?");
$stmt->bind_param("ss", $username, $password);

// 设置参数并执行
$username = $_POST['username'];
$password = $_POST['password'];
$stmt->execute();

// 绑定结果变量
$stmt->bind_result($id);

// 检查是否有匹配的用户
if ($stmt->fetch()) {
    echo "登录成功";
} else {
    echo "用户名或密码错误";
}

// 关闭语句和连接
$stmt->close();
$conn->close();
?>