simple sample paging

<?php
session_start();
/************************
- SIMPLE SAMPLE PAGING -
note        : not yet tested,
              not yet finished
              oh no! ^_^V
created by  : CAHYA DSN
created date: 2012-10-19
*************************/
//Database Configuration
//-------------------
$dbhost='localhost';
$dbuser='test';
$dbpass='test';
$dbname='test';
//Database connection
//-------------------
$db = new mysqli($dbhost, $dbuser, $dbpass, $dbname);
//-- get 1st content id for current page
//--------------------------------------
$page=isset($_GET['page'])?$_GET['page']:0;
$id=0;
$next_id='';
if(isset($_SESSION['pages']) && !empty($_SESSION['pages']))
{
  $id=$_SESSION['pages'][$page];
  if($_SESSION['pages'][$page]<$_SESSION['pagenum'])
  {
    $next_id=' AND id<'.$_SESSION['pages'][$page+1];
  }
}
//show content per page
//-------------------
$sqldetail = 'SELECT id,title,content FROM table WHERE id>='.$id.$next_id.' ORDER BY id DESC';
if ($details = $db->query($sqldetail))
{
   while($row=$details->fetch_object())
   {
     echo "<div class=\"content_box\">\n"
         ."<div class=\"content_title\"><a href=\"?detail=".$row->id."\">".$row->title."</a></div>\n";
         ."<div class=\"content\">".$row->content."</div>\n"
         ."</div>";
   }
   $details->close();
}
//build paging navigation
// paging model : 1|2|3|4|5
//-------------------
$perpage=5; //number of contents to be displayed per page
if(!isset($_SESSION['pages']) || empty($_SESSION['pages']))
{
  $sqlpaging = 'SELECT id FROM table ORDER BY id DESC';
  if ($result = $db->query($sqlpaging))
  {
    $num=$result->num_rows;
    if(num>0)
    {
      echo "<div class=\"navigation\">\n";
      $pages=array();
      $pagenum=ceil($num/$perpage);
      for($i=0;$i<$pagenum-1;$i++)
      {
        $result->data_seek($perpage*$i);
        $row = $result->fetch_object();
        $pages[$i]=$row->id;
        echo ($i==0?'':'|').($page==$i?' '.$i.' ':' <a href="?page='.$i.'">'.($i+1).'</a> ');
      }
      echo "</div>\n";
      $_SESSION['pages']=$pages;
      $_SESSION['pagenum']=$pagenum;
    }
    $result->close();
  }
}else{
  if($_SESSION['pagenum']>0){
    echo "<div class=\"navigation\">\n";
    for($i=0;$i<$_SESSION['pagenum'];$i++){
      echo ($i==0?'':'|').($page==$i?' '.$i.' ':' <a href="?page='.$i.'">'.($i+1).'</a> ');
    }
    echo "</div>\n";
  }
}
// paging model: prev | next
// paging model: first|prev|next|last
// paging model: prev|... 4|5|[6]|7|8 ..|next
$db->close();
?>