登录php中的mysql数据库

<?php
try {
    // 数据库连接参数
    $host = 'localhost';
    $dbname = 'your_database_name';
    $user = 'your_username';
    $password = 'your_password';

    // 创建PDO实例
    $pdo = new PDO("mysql:host=$host;dbname=$dbname;charset=utf8", $user, $password);

    // 设置错误处理模式为异常
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    // 执行查询
    $stmt = $pdo->query('SELECT * FROM users WHERE username = :username AND password = :password');
    $stmt->bindParam(':username', $username);
    $stmt->bindParam(':password', $password);
    $username = $_POST['username'];
    $password = $_POST['password']; // 注意：这里应该对密码进行哈希处理后再进行比较
    $stmt->execute();

    // 处理结果
    $user = $stmt->fetch(PDO::FETCH_ASSOC);
    if ($user) {
        echo '登录成功';
    } else {
        echo '用户名或密码错误';
    }
} catch (PDOException $e) {
    echo '数据库连接失败: ' . $e->getMessage();
}
?>