php+MySQL查询 mysql_num_rows总是返回0，实际上有1条数据

Question

$link=mysql_connect("127.0.0.1:3307","root","");
mysql_query("set names 'utf8'");

$db_selected= mysql_select_db("yuancheng1",$link);

$id=$_GET['id'];
// echo $Id;
$sql="select * from xinxi where id='$id'";
//echo $sql;
$result=mysql_query($sql,$link);
// print_r($result);
$count=mysql_num_rows($result);
echo $count;

Answer 1

$sql能打印出来么，是不是变量外面应该加个大括号