How to create paging display in php

//Establish database connection
$link = mysql_connect("localhost", "mysql_user", "mysql_passWord")
or die("Could not connect: " . mysql_error ());
// Get the current page number
if( isset($_GET['page']) ){
$page = intval( $_GET['page'] );
}
else{
$page = 1;
}
// Number of pages per page
$PageSize = 10;
// Get the total data amount
$sql = "select count(*) as amount from table";
$result = mysql_query($sql);
$row = mysql_fetch_row($result);
$amount = $row['amount'];< /p>
// Calculate how many pages there are in total
if( $amount ){
if( $amount < $page_size ){ $page_count = 1; } //If the total data amount is less than $PageSize, Then there is only one page
if( $amount % $page_size ){ //Get the remainder of the total data amount divided by the number of pages
$page_count = (int)($amount / $page_size) + 1; //If there is a remainder, Then the number of pages is equal to the total data amount divided by the number of each page, rounded up and plus one
}else{
$page_count = $amount / $page_size; //If there is no remainder, the number of pages is equal to the total data amount divided by each page The result of counting
}
}
else{
$page_count = 0;
}
// Page turning link
$page_string = '';
if( $page == 1 ){
$page_string .= 'First page|Previous page|';
}
else{
$page_string .= 'First page|Previous page|';
}
if( ($page == $page_count) | | ($page_count == 0) ){
$page_string .= 'next page|last page';
}
else{
$page_string .= 'Next page|Last page';
}
if( $amount ){
$sql = "select * from table order by id desc limit ". ($page-1)*$page_size .", $page_size ";
$result = mysql_query($sql);
while ( $row = mysql_fetch_row($result) ){
$rowset[] = $row;
}
}else{
$rowset = array();
}
// There is no code for displaying the results, so that is beyond the scope of the discussion. As long as you use foreach, you can easily use the obtained two-dimensional array to display the results
?>

4. OO style code The database connection in the following code is processed using the pear db class

// FileName: Pager.class.php
// Paging class, this class is only used to process data structures and is not responsible for processing display work
Class Pager
 {
var $PageSize; //Number of each page
var $CurrentPageID; //Current page number
var $NextPageID; //Next page
var $PreviousPageID; //Previous page
var $numPages; // Total number of pages
var $numItems; //Total number of records
var $isFirstPage; //Whether it is the first page
var $isLastPage; //Whether it is the last page
var $sql; //sql query statement
function Pager($option)
{
global $db;
$this->_setOptions($option);
// Total number of items
if ( !isset ($this->numItems) )
{
$res = $db->query($this->sql);
$this->numItems = $res->numRows();
}< ;/p>
//Total number of pages
if ( $this->numItems > 0 )
{
if ( $this->numItems < $this->PageSize ){ $this ->numPages = 1; }
if ( $this->numItems % $this->PageSize )
{
$this->numPages= (int)($this->numItems / $this-> ;PageSize) + 1;
}
else
{
$this->numPages = $this->numItems / $this->PageSize;
}
}
else
{
$this->numPages = 0;
}
switch ( $this->CurrentPageID )
{
case $this->numPages == 1:
$this->isFirstPage = true;
$this ->isLastPage = true;
break;
case 1:
$this->isFirstPage = true;
$this->isLastPage = false;
break;
case $this->numPages:
$this->isFirstPage = false;
$this->isLastPage = true;
break;
default:
 $this->isFirstPage = false;
$this->isLastPage = false;
}
if ( $this->numPages > 1 )
{
if ( !$ this->isLastPage ) { $this->NextPageID = $this->CurrentPageID + 1; }
if ( !$this->isFirstPage ) { $this->PreviousPageID = $this->CurrentPageID - 1; }
}
return true;
}
/***
*
* Return the database connection of the result set
* When the result set is relatively large, you can directly use this method to obtain the database connection, and then traverse outside the class, so the overhead is smaller
* If the result set is not very large, you can Directly use getPageData to obtain the result in two-dimensional array format
* The getPageData method also calls this method to obtain the result
*
***/
function getDataLink()
{
if ( $this->numItems )
{
global $db;
$PageID = $this->CurrentPageID;
$from = ($PageID - 1)*$this->PageSize;
$count = $this->PageSize;
$link = $db- >limitQuery($this->sql, $from, $count); //Use Pear DB::limitQuery method to ensure database compatibility
return $link;
}
else
{
return false;
}
}
/***
*
* Returns the result set in the format of a two-dimensional array
*
***/
function getPageData()
{
if ( $this->numItems )
{
if ( $res = $this->getDataLink( ) )
{
if ( $res->numRows() )
{
while ( $row = $res->fetchRow() )
{
$result[] = $row;
}
}
else
{
$result = array();
}
return $result;
}
else
{
return false;
}
}
else
{
return false;
}
}
< ;p>function _setOptions($option)
{
$allow_options = array(
'PageSize',
'CurrentPageID',
'sql',
'numItems'
);
foreach ( $option as $key => $value )
{
if ( in_array($key, $allow_options) && ($value != null) )
{
$this->$key = $value;
}
}
return true;
}
}
?>

#--------------------------

// FileName: test_pager.php
// This is a simple sample code, the code for using the pear db class to establish a database connection is omitted
require "Pager .class.php";
if ( isset($_GET['page']) )
{
$page = (int)$_GET['page'];
}
else
{
$page = 1;
}
$sql = "select * from table order by id";
$pager_option = array(
"sql" => $sql,
 "PageSize" => 10,
"CurrentPageID" => $page
);
if ( isset($_GET['numItems']) )
{
$pager_option[' numItems'] = (int)$_GET['numItems'];
}
$pager = @new Pager($pager_option);
$data = $pager->getPageData() ;
if ( $pager->isFirstPage )
{
$turnover = "Homepage|Previous page|";
}
else
{
$turnover = "Homepage|Previous page|";
}
if ( $pager->isLastPage )
{
$turnover .= "Next page|Last page";
}
else
{
$turnover .="Next page|Last page ";
}
?>

Instructions: This class only processes data and is not responsible for display, because I think it is a bit reluctant to put both data processing and result display into one class. When displaying, the situation and requirements are changeable. It is better to process it according to the results given by the class. A better way is to inherit a subclass of your own based on the Pager class to display different paginations. For example, to display the user pagination list:

class MemberPager extends Pager
{
function showMemberList()
{
global $db;
$data = $this->getPageData();
// Code to display results
// ......
}
}
/// Call
if ( isset($_GET['page']) )
{
$page = (int)$_GET['page'];
}
else
{
$page = 1;
}
$sql = "select * from members order by id";
 $pager_option = array(
"sql" => $sql,
"PageSize" => 10,
"CurrentPageID" => $page
);
if ( isset( $_GET['numItems']) )
{
$pager_option['numItems'] = (int)$_GET['numItems'];
}
$pager = @new MemberPager($pager_option);
$pager-> ;showMemberList();
?>

The second point that needs to be explained is the compatibility of different databases. The way to write a result in different databases is different. of. mysql: select * from table limit offset, rows pgsql: select * from table limit m offset n ...

So, when you want to get the results in the class, you need to use the limitQuery method of the pear db class.