php登录mysql数据库代码

<?php
$servername = "localhost";
$username = "your_username";
$password = "your_password";
$dbname = "your_database";

try {
    // 创建PDO连接
    $conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
    // 设置PDO错误模式为异常
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    // 准备SQL语句
    $stmt = $conn->prepare("SELECT * FROM users WHERE username = :username AND password = :password");
    $stmt->bindParam(':username', $username);
    $stmt->bindParam(':password', $password);

    // 执行查询
    $stmt->execute();

    // 获取结果
    $result = $stmt->fetch(PDO::FETCH_ASSOC);

    if ($result) {
        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();
}

// 关闭连接
$conn = null;
?>