php查询mysql中字段没有返回值

Question

用的是phpstudy自带的数据库
$conn=@mysqli_connect('localhost','root','root') or die("数据库连接失败！");;

mysqli_select_db($conn,"test") or die("您要选择的数据库不存在");

$sql="select * from users";

$result=mysqli_query($sql);

$row=mysqli_fetch_array($result);

echo $row["username"];

运行后没有任何显示，求助大佬

Answer 1

https://www.cnblogs.com/tommy-huang/p/4053819.html