php怎么获取服务器上的数据库连接

try {
    $host = 'localhost';
    $dbname = 'your_database';
    $user = 'your_username';
    $password = 'your_password';

    // 创建PDO实例
    $pdo = new PDO("mysql:host=$host;dbname=$dbname;charset=utf8mb4", $user, $password);
    // 设置PDO错误模式为异常
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    echo "连接成功";
} catch(PDOException $e) {
    echo "数据库连接失败: " . $e->getMessage();
}

$host = 'localhost';
$user = 'your_username';
$password = 'your_password';
$database = 'your_database';

// 创建连接
$conn = new mysqli($host, $user, $password, $database);

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