pagination is not working

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PHP

<?php 
@session_start();
include 'connections.php';
$button = $_POST['submit'];
$search = $_POST['searchvalue']; 
if(strlen($search)<=1)
{
$name = $_POST['name'];
//echo $a;
echo "Search term too short"; // when ever I click the next button in pagination the next result is alwaysing showing "Search Term too short"
}
else{
echo "You searched for $search <hr size='1'></br>";
$search_exploded = explode (" ", $search);
$x = "";
$construct = "";  
foreach($search_exploded as $search_each)
{
$x++;
if($x==1)
$construct .="title LIKE '%$search_each%'";
else
$construct .="AND title LIKE '%$search_each%'";
}

$construct ="SELECT * FROM books WHERE $construct";

$run = mysql_query($construct);
$foundnum = mysql_num_rows($run);
if ($foundnum==0)
echo "Sorry, there are no matching result for $search.</br></br>1.";
else
{
echo "$foundnum results found !<p>";
 }

$per_page = 2; // I set only 2 results per page But its showing all results in one page
$start = $_GET['start'];
$max_pages = ceil($foundnum / $per_page);
if(!$start)
$start=0;
$getquery = mysql_query("SELECT * FROM books WHERE $construct LIMIT $start, $per_page");
while($runrows = mysql_fetch_assoc($run))
{
echo $output;
}
$prev = $start - $per_page;
$next = $start + $per_page;
                       
$adjacents = 3;
$last = $max_pages - 1;
  
if($max_pages > 1)
{  
//previous button
if (!($start<=0))
echo " <a href='server.php?search=$search&submit&start=$prev'>Prev</a> ";   
          
//pages
if ($max_pages < 7 + ($adjacents * 2))   //not enough pages to bother breaking it up
{
$i = 0;  
for ($counter = 1; $counter <= $max_pages; $counter++)
{
if ($i == $start){
echo " <a href='server.php?search=$search&submit=$i'>$counter</a> ";
}
else {
echo " <a href='server.php?search=$search&submit&start=$i'>$counter</a> ";
} 
$i = $i + $per_page;                
}
}
elseif($max_pages > 5 + ($adjacents * 2))    //enough pages to hide some
{
//close to beginning; only hide later pages
if(($start/$per_page) < 1 + ($adjacents * 2))       
{
$i = 0;
for ($counter = 1; $counter < 4 + ($adjacents * 2); $counter++)
{
if ($i == $start){
echo " <a href='server.php?search=$search&submit=$i'>$counter</a> ";
}
else {
echo " <a href='server.php?search=$search&submit=$i'>$counter</a> ";
}
$i = $i + $per_page;                                      
}
                          
}
//in middle; hide some front and some back
elseif($max_pages - ($adjacents * 2) > ($start / $per_page) && ($start / $per_page) > ($adjacents * 2))
{
echo " <a href='server.php?search=$search&submit=0'>1</a> ";
echo " <a href='server.php?search=$search&submit&start=$per_page'>2</a> .... ";
 
$i = $start;                
for ($counter = ($start/$per_page)+1; $counter < ($start / $per_page) + $adjacents + 2; $counter++)
{
if ($i == $start){
echo " <a href='server.php?search=$search&submit&start=$i'>$counter</a> ";
}
else {
echo " <a href='server.php?search=$search&submit&start=$i'>$counter</a> ";
}  
$i = $i + $per_page;               
}
                                  
}
//close to end; only hide early pages
else
{
echo " <a href='server.php?search=$search&submit=0'>1</a> ";
echo " <a href='server.php?search=$search&submit&start=$per_page'>2</a> .... ";
 
$i = $start;               
for ($counter = ($start / $per_page) + 1; $counter <= $max_pages; $counter++)
{
if ($i == $start){
echo " <a href='server.php?search=$search&submit&start=$i'>$counter</a> ";
}
else {
echo " <a href='server.php?search=$search&submit&start=$i'>$counter</a> ";  
}
$i = $i + $per_page;             
}
}
}
          
//next button
if (!($start >=$foundnum-$per_page))
echo " <a href='server.php?search=$search&submit=$next'>Next</a> ";   
}  
echo "</center>";
}
 ?>

I done with my search engine with pagination, but pagination is not working properly when ever I click the next button It is always showing Search term is too short i.e in first if condition in search logic. and next Thing is I set only 2 results per page but it is also not working. please anyone help me