Pagination Class calculates incorrectly - php

Question

ive written a pagination class and it looks like its not outputting the correct amount of rows. i have a table full of 51 records and instead it shows only 30 records and as for the pages it shows only page 1 where it should show page 1 and 2. the pages are viewed by going to page=1 as a browser param. when i try to view page=2 i see the rest of the records. here is the class.
include_once("class.db.php");
class Pagination {
var $param;
var $perPage;
var $adjacents;
var $start;
var $sql;
var $pageName;
function __construct() {
$this->db = new MysqlDB;
$this->db->connect();
}
function setParam() {
if(isset($_GET['page']) && is_numeric($_GET['page']) && ($_GET['page'] > 0)) {
$this->param = $_GET['page'];
} else {
$this->param = 1;
}
}
function setIndex() {
$this->setParam();
return $this->start = ($this->param * $this->perPage) - $this->perPage;
}
function showPagination() {
$qRows = $this->db->query($this->sql);
$numRows = $this->db->num_rows($qRows);
$numOfPages = ceil($numRows / $this->perPage);
$param = $this->param;
$pageName = $this->pageName;
print "<div class='pagination'>";
print "<a href='$this->pageName?page=1' class='previous-off'> First </a>";
// ----------------------------------------------------------------------------
// PRINT ALL PAGES TO THE LEFT //
if(($param - $this->adjacents) > 1) {
print "<span>...</span>";
$lowerLimit = $param - $this->adjacents;
//print all on left side.
for($i = $lowerLimit; $i< $param; $i++) {
print "<a href='$pageName?page=$param = $i'> $i </a>";
}
} else {
//print all numbers between current page and first page.
for($i = 1; $i < $param; $i++) {
print "<a href='$pageName?page=$i'> $i </a>";
}
}
// ----------------------------------------------------------------------------
//print current page
if(($param != 0) && ($param != $numOfPages)) {
print "<span class='current'>$param</span>";
}
// ----------------------------------------------------------------------------
//PRINT ALL PAGES TO THE RIGHT
if(($param + $this->adjacents) < $numOfPages) {
$upperLimit = $param + $this->adjacents;
for($i=($param + 1); $i<=$upperLimit; $i++) {
print "<a href='$pageName?page=$i'> $i </a>";
}
print "<span>...</span>";
} else {
//print all page numbers if out of padded range
for($i = $param + 1; $i<$numOfPages; $i++ ) {
print "<a href='$pageName?page=$i'> $i </a>";
}
}
// ----------------------------------------------------------------------------
$lastPage = $numOfPages - 1;
print "<a class='next' href='$pageName?page=$lastPage'> Last </li>";
print "</div>";
}
function getData() {
$query = $this->sql;
$this->start = $this->setIndex();
return "$query LIMIT $this->start, $this->perPage";
}
}
this is how i use the class:
$db = new MysqlDB;
$paginate = new Pagination;
$paginate->pageName = "index.php"; //sets the page to use
$paginate->perPage = 10; //show num of records per page
$paginate->adjacents = 3; //current page adjacent to
$paginate->sql = "select * from tbl_products"; //the main query
$query = $db->query($paginate->getData());
while($row = mysql_fetch_object($query)) {
print $row->pName."<br/>";
}
$paginate->showPagination(); //shows the pagination div

Answer 1

In function setIndex you have to write:
return $this->start = (($this->param - 1) * $this->perPage) - $this->perPage;
because a query should look like:
for page 1: SELECT ... LIMIT 0,[nr_of_pages]
for page 2: SELECT ... LIMIT [nr_of_pages]*1,[nr_of_pages]
...