从数据库中获取用户名以在文本框中显示

Question

我似乎无法将数据库中的用户名显示在文本框中。这些是我的代码：

$con = new mysqli_connect("", "", "", "");

$username = $_GET['username'];
$query = "SELECT username FROM users WHERE username=?";
$result = mysqli_query($query);
if (!$result) 
{
    die("Error: Data not found..");
}
$test = mysqli_fetch_array($result);
$username=$test['username'];

input type =“text”name =“username”id =“username”value =“echo $ username;？＆gt;”