Search using php isset not working

if (isset($_GET['k']))
{

    $k=$_GET['k'];
    $query="SELECT * FROM `upload` WHERE `keywords` LIKE '%$k%'  ";

 @mysql_connect("localhost","root","") or die("error");
 mysql_select_db("lol") or die ("error");

 $query= mysql_query($query);
  $numrows=mysql_num_rows($query);
 if($numrows >0)
 {
    while ($row =mysql_fetch_assoc($query))
    {

    $keywords=$row['keywords'];
    $name2=$row['name2'];
    $URL=$row['URL'];
    echo "<h2><a href='$URL'>$name2</a></h2><br/><br/>";

    }
 }
 else
 echo "no result found";
 }
 else
 {
    echo "please enter some value in search";
 }

?>

I am making a simple search engine The issue is that if don't pass a value in search bar it shows all the results from database .To make it correct I use ISSET but it is not working plz help me me for this. Here is the attached code