php中分页及sqlHelper类实例有哪些？

<?php
/**
 * Created by JetBrains PhpStorm.
 * User: lee
 * Date: 13-7-26
 * Time: 下午8:30
 * To change this template use File | Settings | File Templates.
 */
class SqlHelper{
 private $mysqli;
 private static $host="localhost";
 private static $user="root";
 private static $pwd="";
 private static $db="world";
 private $sql=false;
 private $result=false;
 function __construct(){
  $this->mysqli=new MySQLi(self::$host,self::$user,self::$pwd,self::$db);
  if($this->mysqli->connect_error){
   die("连接数据库失败！ ".$this->mysql->connect_error);
  }
  $this->mysqli->query("set names utf8");
 }
 function execute_dql_all($sql){
  //执行查询语句
  $arr=array();
  $this->result=$this->mysqli->query($sql) or die ($this->mysql->connect_error);
  //将数据转存到$arr数组中
  while($row=mysqli_fetch_array($this->result,MYSQL_BOTH)){
   $arr[]=$row;
  }
  $this->result->free();
  return $arr;
 }
 function execute_dql_num($sql){
  //执行查询语句
  $arr=array();
  $this->result=$this->mysqli->query($sql) or die ($this->mysql->connect_error);
  //将数据转存到$arr数组中
  while($row=mysqli_fetch_array($this->result,MYSQLI_NUM)){
   $arr[]=$row;
  }
  $this->result->free();
  return $arr;
 }
 function execute_dql_assoc($sql){
  //执行查询语句
  $arr=array();
  $this->result=$this->mysqli->query($sql) or die ($this->mysql->connect_error);
  //将数据转存到$arr数组中
  while($row=mysqli_fetch_array($this->result,MYSQLI_ASSOC)){
   $arr[]=$row;
  }
  $this->result->free();
  return $arr;
 }
 //查询某表中的记录数
 function execute_dql_counts($table,$id="*"){
  $this->sql="select count($id) from $table";
  $this->result=$this->mysqli->query($this->sql);
  $row=mysqli_fetch_all($this->result);
  $this->result->free();
  return $row[0][0];
 }
 function execute_dml($sql){
  //执行正删改
  $this->result=$this->mysqli->query($sql);
  if(!$this->result){
   return -1;//执行正删改失败
  }else{
   if($this->mysqli->affected_rows>0){
    return 1;//执行正删改成功，影响行数
   }else{
    return 0;//执行正删改成功，但没有影响行数
   }
  }
 }
}

<?php
/**
 * Created by JetBrains PhpStorm.
 * User: lee
 * Date: 13-7-27
 * Time: 下午2:48
 * To change this template use File | Settings | File Templates.
 */
header("Content-type:text/html;charset=utf-8;");
require_once("SqlHelper.php");
class Paging {
 private $sqlHelper=false;
 private $pageCount=false;//页数
 private $counts=false;//总记录数
 private $returnArr=false;//分页超链接的分页
 function __construct(){
  $this->sqlHelper=new SqlHelper();
  $this->returnArr=array();
 }
 /*
  * 参数说明
  *
  * $table 分页时对那个表的数据分页
  * $id 辅助查询当前分页的数据表的总记录数
  * $pageSize 每页显示多少条信息记录数
  * $pagingSize 分页栏每次循环显示出来的个数
  * $nowPage 当前是第几页，默认第一页
  * $href 分页栏的超链接将要往哪里连接
  */
 function paging_prev_next($table,$id="*",$pageSize,$pagingSize,$nowPage=1,$href){
  $this->counts=$this->sqlHelper->execute_dql_counts($table,$id);
  $this->pageCount=ceil($this->counts/$pageSize);
  $this->returnArr["count"]=$this->counts;
  $this->returnArr["start"]=($nowPage-1)*$pageSize;
  $this->returnArr["limit"]=$pageSize;
  if($nowPage>$this->pageCount || $nowPage<=0){
   return false;
  }
  $t=(ceil($nowPage/$pagingSize)-1)*$pagingSize+1;
  $pre=$nowPage-$pagingSize;
  $nex=$nowPage+$pagingSize;
  echo "
   <span class='paging-list-a paging-list-a-withBg'>{$nowPage}/{$this->pageCount}</span>
   <a href='{$href}?nowPage={$pre}' class='paging-list-a'><</a>";
  for($i=$t;$i<$t+$pagingSize;$i++){
   if($i*$pageSize>$this->pageCount*$pageSize){
    break;
   }else{
    if($nowPage==$i){
     echo "
     <a href='{$href}?nowPage={$i}' class='paging-list-a paging-list-a-withBg'>{$i}</a>";
    }else{
     echo "
     <a href='{$href}?nowPage={$i}' class='paging-list-a'>{$i}</a>";
    }
   }
  }
  echo "
   <a href='{$href}?nowPage={$nex}' class='paging-list-a'>></a>";
  return $this->returnArr;
 }
}

/**
 * Created by JetBrains PhpStorm.
 * User: lee
 * Date: 13-7-27
 * Time: 下午5:56
 * To change this template use File | Settings | File Templates.
 */
.paging-list-a{
 border:1px solid #b5b5af;
 background-color:#efebed;
 font-family: 'Meiryo UI';
 font-size: 16px;
 font-weight: 600;
 padding: 0px 8px 0px 8px;
 /*cursor: pointer;*/
 text-decoration: none;
 color: #292927;
}
.paging-list-a-withBg{
 background-color: #1D92E2;
 color: white;
}

<!DOCTYPE html>
<html>
<head>
 <title></title>
 <link rel="stylesheet" type="text/css" href="paging-list-link.css">
</head>
<body>
<?php
header("Content-type:text/html;charset=utf-8;");
require_once 'Paging.php';
$paging=new Paging();
//参数说明
/*
 * $table 分页时对那个表的数据分页
 * $id 辅助查询当前分页的数据表的总记录数
 * $pageSize 每页显示多少条信息记录数
 * $pagingSize 分页栏每次循环显示出来的个数
 * $nowPage 当前是第几页，默认第一页
 * $href 分页栏的超链接将要往哪里连接，当前页链接地址
 */
//控制起始页为
$nowPage=1;
if(isset($_GET["nowPage"])){
 $nowPage=$_GET["nowPage"];
}
//定义分页所需参数
$meiyexiansi=10;
$meiyelianjieshu=10;
$receiveArr=array();
$receiveArr=$paging->paging_prev_next("city","ID",$meiyexiansi,$meiyelianjieshu,$nowPage,"usePaging.php");
//容错判断
if(!$receiveArr){
 return;
}
//查询每页需要显示的数据，大小限制存在 $receiveArr 数组中
$sqlHelper=new SqlHelper();
$result=$sqlHelper->execute_dql_num("select * from city limit ".$receiveArr['start'].",".$receiveArr['limit']."");
echo "<pre>";
print_r($result);
echo "</pre>";
?>
</body>
</html>

if($nowPage>$this->pageCount || $nowPage<=0){
 return false;
}