Доработать фильр

<form method="get" action="search_filter.php">
<ul>
<li><a>Поиск по разделам</a>
<ul class="checkbox-brand">
 
<?php 
$result = mysql_query("SELECT * FROM category WHERE type='стикеры'",$link);
 
if (mysql_num_rows($result) > 0)
{
    
    $row = mysql_fetch_array ($result);
    
    do 
    {
        $checked_brand = "";
        if($_GET["brand1"])
        {
            if(in_array($row["id"], $_GET["brand1"]))
            {
                $checked_brand = "checked";
            }
        }
        echo '
        <li><input '.$checked_brand.'  type="checkbox" name="brand1[]" value="'.$row["id"].'" id="checkboxbrand'.$row["id"].'"><label for="checkboxbrand'.$row["id"].'">'.$row["brand1"].'</label></li>
        ';
    }
    while ($row = mysql_fetch_array ($result));
    
}
 
?>
</ul>
</li>
</ul>
 
<center><input type="submit" name="submit" id="button-param-search" value="Найти"></center>
 
</form>

if ($_GET["brand1"])
{
    $check_brand = implode(',',$_GET["brand1"]);
}
 
if (!empty($check_brand))
{
    if (!empty($check_brand)) $query_brand = "AND brand_id IN($check_brand)";
    
}
$result = mysql_query("SELECT * FROM table_produkts WHERE visible='1' $query_brand  ORDER BY  products_id  DESC $query_start_num", $link);

$start = $page * $num - $num;
    
$query_start_num = "LIMIT $start, $num";

if($page !=1) 
{
$pstr_prev = '<li><a class="pstr_prev" href="search_filter.php?brand1='.$check_brand.'&page='.($page -1).'">&lt;</a></li>';
}

page='.($page -1).

$pstr_prev = '<li><a class="pstr_prev" href="search_filter.php?page='.($page -1).'">&lt;</a></li>';