PHP分页详细讲解（有实例）

<?php
// 建立数据库连接
$link = mysql_connect("localhost", "mysql_user", "mysql_passWord")
      or die("Could not connect: " . mysql_error());
// 获取当前页数
if( isset($_GET[page]) ){
   $page = intval( $_GET[page] );
}
else{
   $page = 1;
}
// 每页数量
$PageSize = 10;
// 获取总数据量
$sql = "select count(*) as amount from table";
$result = mysql_query($sql);
$row = mysql_fetch_row($result);
$amount = $row[amount];
// 记算总共有多少页
if( $amount ){
   if( $amount < $page_size ){ $page_count = 1; }               //如果总数据量小于$PageSize，那么只有一页
   if( $amount % $page_size ){                                  //取总数据量除以每页数的余数
       $page_count = (int)($amount / $page_size) + 1;           //如果有余数，则页数等于总数据量除以每页数的结果取整再加一
   }else{
       $page_count = $amount / $page_size;                      //如果没有余数，则页数等于总数据量除以每页数的结果
   }
}
else{
   $page_count = 0;
}

// 翻页链接
$page_string = ;
if( $page == 1 ){
   $page_string .= 第一页|上一页|;
}
else{
   $page_string .= <a href=?page=1>第一页</a>|<a href=?page=.($page-1).>上一页</a>|;
}
if( ($page == $page_count) || ($page_count == 0) ){
   $page_string .= 下一页|尾页;
}
else{
   $page_string .= <a href=?page=.($page+1).>下一页</a>|<a href=?page=.$page_count.>尾页</a>;
}
// 获取数据，以二维数组格式返回结果
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();
}
// 没有包含显示结果的代码，那不在讨论范围，只要用foreach就可以很简单的用得到的二维数组来显示结果
?>

<?php
// FileName: Pager.class.php
// 分页类，这个类仅仅用于处理数据结构，不负责处理显示的工作
Class Pager
{
   var $PageSize;             //每页的数量
   var $CurrentPageID;        //当前的页数
   var $NextPageID;           //下一页
   var $PreviousPageID;       //上一页
   var $numPages;             //总页数
   var $numItems;             //总记录数
   var $isFirstPage;          //是否第一页
   var $isLastPage;           //是否最后一页
   var $sql;                  //sql查询语句

  function Pager($option)
   {
       global $db;
       $this->_setOptions($option);
       // 总条数
       if ( !isset($this->numItems) )
       {
           $res = $db->query($this->sql);
           $this->numItems = $res->numRows();
       }
       // 总页数
       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;
   }

   /***
    *
    * 返回结果集的数据库连接
    * 在结果集比较大的时候可以直接使用这个方法获得数据库连接，然后在类之外遍历，这样开销较小
    * 如果结果集不是很大，可以直接使用getPageData的方式获取二维数组格式的结果
    * getPageData方法也是调用本方法来获取结果的
    *
    ***/

   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);   //使用Pear DB::limitQuery方法保证数据库兼容性

           return $link;
       }
       else
       {
           return false;
       }
   }

   /***
    *
    * 以二维数组的格式返回结果集
    *
    ***/

   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;
       }
   }

   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;
   }
}
?>
<?php
// FileName: test_pager.php
// 这是一段简单的示例代码，前边省略了使用pear db类建立数据库连接的代码
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 = "首页|上一页|";
}
else
{
   $turnover = "<a href=?page=1&numItems=".$pager->numItems.">首页</a>|<a href=?page=".$pager->PreviousPageID."&numItems=".$pager->numItems.">上一页</a>|";
}
if ( $pager->isLastPage )
{
   $turnover .= "下一页|尾页";
}
else
{
   $turnover .= "<a href=?page=".$pager->NextPageID."&numItems=".$pager->numItems.">下一页</a>|<a href=?page=".$pager->numPages."&numItems=".$pager->numItems.">尾页</a>";
}
?>

<?php
Class MemberPager extends Pager
{
   function showMemberList()
   {
       global $db;

       $data = $this->getPageData();
// 显示结果的代码
       // ......
   }
}
/// 调用
if ( isset($_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();
?>