如何检查SQL（mysql）结果。 PHP

Question

In my php.Mysql ($sql) result should be 1.Sysum should not be empty in another word, mysql_num_rows($sel) > 0 should be true.

But actually,mycode can not work.I don't know why.Who can help me?

$conn = new PDO('mysql:host=localhost;port=3306;dbname=hpc' , 'root' , 'Yd');
$Name=$_COOKIE['PName'];
$sql = "select sysnum from hpc where handler='".$Name."' and stat='N';";
$sel=$conn->query($sql);
if(mysql_num_rows($sel) > 0)
{       
 mycode;
}

Answer 1

fetch result into an array and count items using count function, like this:

$Name=$_COOKIE['PName'];
$sql = "select sysnum from hpc where handler='".$Name."' and stat='N';";
$sel = $conn->query($sql)->fetchall();
if(count($sel) > 0){       
 mycode;
}