Hỏi về phân trang cho trang danh mục

                        <?php


                        if(!$_GET['category']){
                            echo "khong co gi";
                        }
                        else{
                            $category = $_GET['category'];
                            //$page = $_GET['page'];


                            
                        }
                        ?>


                        <?php


                        if(!$_GET['page']){
                            $page = 1;
                            
                            
                        }
                        else{
                            $page = $_GET['page'];
                        }
                        $max_result = 12;
                        $index_row=$page * $max_result - $max_result;
                        ?>






                        <?php


                        $sql = "SELECT * FROM sanpham WHERE id_danhmuc = '{$category}' LIMIT $index_row, $max_result";
                        $query=mysql_query($sql);
                        while($row=mysql_fetch_array($query)){


                            ?>
                            <li>
                                <a href="details.php?id=<?php echo $row['id_sanpham'] ?>"><img src="Images/<?php echo $row['img_sanpham']; ?>"/></a><br>
                                <?php echo $row['ten_sanpham']; ?><br>
                                <?php echo $row['gia_sanpham']; ?>
                                <span id="gia_sanpham" style="color: red;">VNĐ</span>
                            </li>
                            <?php }
                            ?>
                        </ul>
                        
                        <p id=paging><br></p>
                        <?php
                                            // Tinh tong so sanpham co trong CSDL
                        $total_row = mysql_num_rows(mysql_query("SELECT * FROM sanpham WHERE id_danhmuc = '{$category}'"));
                                            // Lam tron so trang co duoc dua vao tong so sanpham va so sanpham tren moi trang
                        $total_page = ceil($total_row/$max_result);
                        if(!$total_page)
                        {
                            echo 'Lỗi SQL: '.mysql_error();
                            echo "\r\n<br />";
                            echo 'SQL: '.$total_page;
                            exit;
                        }
                        // Khai bao bien danh sach so trang
                        $list_page = '';
                            // Tao nut Prev
                        $prev = $page - 1;
                        if($page > 1){
                            $list_page .= "<a href=".$_SERVER['PHP_SELF']."?page=$prev>Prev </a>";
                        }
                        // Liet ke danh sach so trang
                        for($i=1; $i<=$total_page; $i++){
                            if($page == $i){
                                $list_page .= "<b>$i </b>";
                            }
                            else{
                                $list_page .= "<a href=".$_SERVER['PHP_SELF']."?page=$i>".$i." </a>";
                            }
                        }
                        // Tao nut Next
                        $next = $page + 1;
                        if($page < $total_page){
                            $list_page .= "<a href=".$_SERVER['PHP_SELF']."?page=$next>Next</a>";
                        }
                        // Suat ra thanh phan trang
                        ?>
                        <p id=paging>
                            <?php
                            echo $list_page;
                            ?>
                        </p>

<?php
$max_item = 12; //so luong san pham hien thi tren moi trang
$show_page = 10; //so luong nut Page toi da hien thi tren thanh phan trang


if(!isset($_REQUEST['category'])){ //khong gui danh muc
    echo '<div class="waring">Chua gui danh muc san pham</div>';
} else {
    //lay du lieu duoc truyen
    $category = ($_REQUEST['category'] != "") ? $_REQUEST['category'] : 0;
    $page = ((isset($_REQUEST['page'])) && ($_REQUEST['page'] != ""))? $_REQUEST['page'] : 1;
    
    if(!preg_match("/\A\d{1,}\z/", $category) || !preg_match("/\A\d{1,}\z/", $page)){ //phong chong tan cong SQL injection
         echo '<div class="waring">Ban dang co gang tan cong SQL injection</div>';
    } else {
        
        //tinh so trang co the hien thi
        $sql = "SELECT *
                FROM sanpham
                WHERE id_danhmuc = '{$category}'";
        
        $all_item = mysql_query($sql) or die("<div class=\"waring\">Loi truy van danh sach san pham</div>");
        $num_item = mysql_num_rows($all_item);
        
        if($num_item == 0){ // kiem tra danh muc truy cap co san pham nao hay khong
            echo '<div class="message">Chua co san pham nao trong danh muc chi dinh</div>';
        } else {
            $max_page = ceil($num_item/$max_item);
            
            if (($page < 1) || ($page > $max_page)){ //kiem tra trang can hien thi co vuot qua gioi han so trang hay khong
                echo '<div class="waring">Trang san pham khong ton tai</div>';
            } else {
                $index = $page - 1;
                $sql = "SELECT *
                        FROM sanpham
                        WHERE id_danhmuc = '{$category}'
                        LIMIT {$index}, {$max_item}";
                $limit_item = mysql_query($sql) or die("<div class=\"waring\">Loi truy van phan trang san pham</div>");
                
                //hien thi danh sach san pham
                echo '<div class="list-item"><ul>';
                while($item = mysql_fetch_array($limit_item)){
                    echo <<<EOF
                    <li>
                        <div class="item-poster"><a href="details.php?id={$item['id_sanpham']}"><img src="images/{$item['img_sanpham']}" /></a></div>
                        <div class="item-label"><a href="details.php?id={$item['id_sanpham']}">{$item['ten_sanpham']}</a></div>
                        <div class="item-price">{$item['gia_sanpham']} VND<div>
                    </li>
EOF;
                }
                echo '</ul></div>';
                
                //hien thi thanh phan trang
                echo '<div class="pagebar"><ul>';
                    //hop Page
                    echo "<li>Page {$page} of {$max_page}</li>";
                    //nut First
                    if($max_page > $show_page){
                        echo "<li><a href=\"{$_SERVER['PHP_SELF']}?category={$category}&page=1\">First</a></li>";
                    }
                    //nut Prev
                    if($page != 1){
                        $prev = $page - 1;
                        echo "<li><a href=\"{$_SERVER['PHP_SELF']}?category={$category}&page={$prev}\">Prev</a></li>";
                    }
                    //nut Page
                    if($max_page > $show_page){
                        $limit_page = (($page + $show_page) > $max_page) ? $max_page : ($page + $show_page - 1);
                        for($i = $page; $i <= $limit_page; $i++){
                            echo "<li><a href=\"{$_SERVER['PHP_SELF']}?category={$category}&page={$i}\">{$i}</a></li>";
                        }
                    } else {
                        for($i = 1; $i <= $max_page; $i++){
                            echo "<li><a href=\"{$_SERVER['PHP_SELF']}?category={$category}&page={$i}\">{$i}</a></li>";
                        }
                    }
                    //nut Next
                    if($page != $max_page){
                        $next = $page + 1;
                        echo "<li><a href=\"{$_SERVER['PHP_SELF']}?category={$category}&page={$next}\">Next</a></li>";
                    }
                    //nut First
                    if($max_page > $show_page){
                        echo "<li><a href=\"{$_SERVER['PHP_SELF']}?category={$category}&page={$max_page}\">Last</a></li>";
                    }
                echo '</ul></div>';
            }
        }
    }
}
?>