无法在while循环之外访问SQL数据

皮卡丘不卡

当我将SQL查询结果保存在变量($ test2中的代码)，变量在while循环是空的。为什么？
- j2 O! m$ g2 B! f变量通常在此循环中定义(见$ test1）。SQL查询也可以。
$connection = new mysqli($servername,$username,$password,$dbname) or die("Error: " . mysqli_error($connection));$query = "SELECT * FROM Table ORDER BY `id` ASC";$result = mysqli_query($connection,$query);while($row = mysqli_fetch_object($result))    $test1 = "some text";    $test2 = $row->id;    echo $row->id // Output is the id -> works}echo $test1; // Output is "some text" -> worksecho $test2; // Output is nothing -> doesn't work. Why?               
    解决方案: