PHPでデータを削除する方法

<?php
// header(&#39;Content-type:text/html;charset=utf-8&#39;);
// $conn = @mysqli_connect(&#39;localhost&#39;,&#39;root&#39;,&#39;123456&#39;,&#39;itsource&#39;);
 include(&#39;./conn.php&#39;);
 
$id = $_GET[&#39;id&#39;];
// echo $title.$autor.$source.$content;
$sql = "delete from news where id = $id";
$res  = mysqli_query($conn,$sql);
if($res)
{
echo &#39;<script>alert("删除成功");  location.href="list.php";</script>&#39;;
}else {
echo &#39;删除失败&#39;.mysql_error($conn);
}
echo &#39;<a href="list.php">返回</a>&#39;;
?>