Фильтр на php + база данных

<?
 if ($_GET["class"])
{
    $check_class = implode(',',$_GET["class"]);
}
 
    if (!empty($check_class))
    {
        if(!empty($check_class)) $query_class = " AND class_id IN($check_class)";
        
    }
    
    
    $result = mysql_query("SELECT * FROM cards $query_class", $link);
    
 
if (mysql_num_rows($result) > 0 )
{
  
  $row = mysql_fetch_array($result);
  
do 
  {
  echo '
  <img src="/wp-content/uploads/cards/'.$row["img"].'">
  
  ';
  
  }
  
    while ($row = mysql_fetch_array($result));
    
    }
?>
 
 
<form method="GET" action="/wp-content/themes/point/cards_filter.php">
  
<div id="card-class">
 
<? 
$result = mysql_query("SELECT * FROM class", $link);
if (mysql_num_rows($result) > 0)
{
$row = mysql_fetch_array($result);
do 
{
 
echo ' <li><input type="checkbox" name="class[]" value="class_id'.$row["id"].'" id="class_id'.$row["id"].'" /><label for="class_id'.$row["id"].'">'.$row["class"].'</label></li>
    ';
    
}
    while ($row = mysql_fetch_array($result));  
}
?>
 
 
<input type="submit" name="Применить" id="button-filter" value="Применить" />
 
</div>