如何在SQL中找到最大值，并使用PDO将其读入PHP？

$db_host = '数据库主机名';
$db_name = '数据库名称';
$db_user = '数据库用户名';
$db_pass = '数据库密码';

try {
    $pdo = new PDO("mysql:host=$db_host;dbname=$db_name", $db_user, $db_pass);
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    echo "成功连接到数据库";
} catch(PDOException $e) {
    echo "数据库连接失败: " . $e->getMessage();
}

SELECT MAX(value) AS max_value FROM numbers;

$sql = "SELECT MAX(value) AS max_value FROM numbers";
$stmt = $pdo->query($sql);
$result = $stmt->fetch(PDO::FETCH_ASSOC);
$max_value = $result['max_value'];

echo "最大值为：" . $max_value;