删除“where子句”中的未知列“int 值”

我有一个表，它有一个名为link_id的A_I列。当我这样运行时：

$link_id = 32;
$query1 = "DELETE FROM links WHERE link_id = $link_id";
if(!mysql_query($query1,$connection));
{
    die(mysql_error($connection));
}

它工作成功，但是当我尝试使用 C# WebRequest 执行此操作时：

WebRequest request = WebRequest.Create("http://www.mywebsite.com/deleteLink.php");
request.Method = "POST";
string post = "link_id=" + id //type string;
byte[] postBytes = Encoding.UTF8.GetBytes(post);
request.ContentLength = postBytes.Length;
request.ContentType = "application/x-www-form-urlencoded";
Stream dataStream = await request.GetRequestStreamAsync();
dataStream.Write(postBytes, 0, postBytes.Length);
WebResponse response = await request.GetResponseAsync();
return new StreamReader(response.GetResponseStream()).ReadToEnd();

返回："where 子句"中的未知列"32"

我哪里做错了？谢谢。