一个继承自PDO类的自动分页类

1、新建一个PHP文件，文件名为pdopage_class.php，将以下代码粘贴进去。代码如下： <?php/** * 类名: PdoPage * 作者：谢声涛 [e-mail] * 描述: 继承自PDO类，增加了自动分页功能，类似MS ADO组件的自动分页功能。 *///-------------开始-----------------------------------class PdoPage extends PDO {     public $RecordCount = 0;    // 记录集的记录总数 public $AutoPage = false;   // 启用自动分页功能 public $PageSize = 0;       // 每页的记录行数 public $CurrentPage = 0;    // 当前页 public $Pages = 0;          // 总页数 public $BOF = false;        // 游标到记录集之前 public $EOF = false;        // 游标到记录集之后  private $RecordSet = null;  // 记录集  private $mCurrentRow = -1;  // 记录集中当前游标位置 private $Rows = 0;          //总记录数  // 关闭连接 public function Close(){unset($this);}  // 分页查询 public function QueryEx($SqlString){  // 是否启用自动分页功能  if($this->AutoPage){   // 检查PageSize参数   if ($this->PageSize <=0) die("警告：PageSize不能为负数或零。");   // 计算总记录数   $rs = @parent::query($this->rebuildSqlString($SqlString));   $this->Rows = $rs->fetchColumn();    // 计算总页数   if ($this->Rows < $this->PageSize) {$this->Pages = 1;}   elseif ($this->Rows % $this->PageSize) {$this->Pages = intval($this->Rows/$this->PageSize)+1;}   else {$this->Pages = intval($this->Rows/$this->PageSize);}   // 约束CurrentPage值，使之位于1到Pages之间。   if($this->CurrentPage < 1) {$this->CurrentPage =1;}   if($this->CurrentPage > $this->Pages) {$this->CurrentPage = $this->Pages;}     //计算偏移量   $Offset = $this->PageSize * ($this->CurrentPage - 1);   // 重组SQL语句,SqlString有分号则去掉   $SqlString = str_replace(";","",$SqlString) . " LIMIT $Offset,$this->PageSize;";  }  // 查询并返回记录集  $rs = new PDOStatement();  $rs = @parent::query($SqlString);  $this->RecordSet = $rs->fetchAll();//returns an array.  $this->RecordCount = count($this->RecordSet);  if(!$this->AutoPage){$this->Pages = (!$this->RecordCount)?0:1;}  return $this->RecordCount; }  // 取得字段值 public function FieldValue($FieldName=""){  return ($this->RecordSet[$this->mCurrentRow][$FieldName]); }  //--------移动记录集游标--------------------------------------------- public function Move($RowPos){  if ($RowPos<0) $RowPos = 0;  if ($RowPos > $this->RecordCount-1) $RowPos = $this->RecordCount-1;  $this->mCurrentRow = $RowPos;  $this->EOF = false;  $this->BOF = false;   } public function MoveNext(){  if($this->mCurrentRow < $this->RecordCount-1){   $this->mCurrentRow++;      $this->EOF = false;   $this->BOF = false;  }  else{   $this->EOF = true;  } } public function MovePrev(){  if($this->mCurrentRow > 0){   $this->mCurrentRow--;   $this->EOF = false;   $this->BOF = false;  }else{   $this->BOF = true;  }  } public function MoveFirst(){  $this->mCurrentRow = 0;  $this->EOF = false;  $this->BOF = false; }  public function MoveLast(){  $this->mCurrentRow = $this->RecordCount-1;  $this->EOF = false;  $this->BOF = false; } //-------------------------------------------------- // 用于执行插入、修改、删除等操作 public function Execute($SqlString){  return @parent::query($SqlString); } //-----------------私有函数----------------------------- // 重新构造SQL语句，如将"select * from tb2"改写为"select count(*) from tb2"，旨在提高查询效率。 private function rebuildSqlString($SqlString){  if(preg_match("/select[ ,./w+/*]+ from/",$SqlString,$marr)){     $columns = preg_replace("/select|from/","",$marr[0]);    $columns = preg_replace("//*/","/*",$columns);   $result = preg_replace("/$columns/"," count(*) ",$SqlString);    return $result;  } }  //-------------结束-----------------------------------}//-------------结束-----------------------------------?>2、使用示例：请根据自己的情况修改MySQL用户名、密码、数据库名等信息。<?include_once("./pdopage_class.php");$db = new PdoPage("mysql:host=localhost;dbname=mydb","root","123456");$db->Execute("set character set gbk;");$db->AutoPage = false;$db->PageSize = 6;$db->CurrentPage = 1;$db->QueryEx("select * from tb2;");$db->MoveFirst();while (!$db->EOF) { echo  $db->FieldValue("id"),"/t",$db->FieldValue("name"),"/t",$db->FieldValue("age"),"/n"; $db->MoveNext();}$db->Close();?>