数据库操作类（PHP/mysql）

<?php
/* 数据库查询类  start*/

class Database
{

    var $dbhostname;
    var $dbname;
    var $dbuser;
    var $dbpassword;
    var $connid;
    var $query;
    var $result;
    var $resultid;
    var $insertid;
    var $rows;
    var $errCode             = 0;
    var $errString         = "";
    var $debugString  = "";
  var $xml                    = "";

    /* 构造函数 */
    function Database()
    {

        $this->dbhostname    = "localhost";        //登录数据库主机名
        $this->dbname          = "yourdb";             /数据库名
        $this->dbuser          = "root";                    //数据库登录用户名
        $this->dbpassword    = "";                         //数据库登录密码
        $this->_connect();                                    //连接数据库
        $this->_db_select();                                //选择数据库

    }

    /* 数据库执行函数, $type 执行操作类型, ""为查询, "update"为更新, "insert"为插入, "delete"为删除 */
    function db_query($sql,$type)
    {

            $this->query = $sql;
            if ($this->_query())
            {

                if(empty($type))
                {
                    $this->_num_rows();                              //返回查询的函数
                    $this->result = $this->_fetch_array();  //返回查询结果
                }
                if ($type == "insert")
                {
                    $this->insertid=@mysql_insert_id();            //返回插入的ID自动增量
                }
                return true;
            }
            else
                return false;

    }

    /* 数据库结果生成XML */
  function createXML($itemroot="child",$item="root")
  {
      $dom = new DOMDocument("1.0","utf-8");
      $dom->preserveWhiteSpace = false;
      $dom->formatOutput = true;
    $rootNode = $dom->createElement($item);
        for($i=0;$i<count($this->result);$i++)
      {
      $itemNode = $dom->createElement($itemroot);
          foreach($this->result[$i] as $key=>$value)
          {
                  //$value = iconv("gb2312","utf-8",$value);
                  $tmpNode = $dom->createElement($key,$value);
                  $itemNode->appendChild($tmpNode);
          }
          $rootNode->appendChild($itemNode);
      }
      $dom->appendChild($rootNode);
      if ($this->xml = $dom->saveXML())
          return $this->xml;
      else
          return false;
  }

  /* 连接数据库 */
    function _connect()
    {


        $this->connid = @mysql_connect($this->dbhostname,$this->dbuser,$this->dbpassword);
        if (false == $this->connid)
        {
            $this->errCode = 1;
            $this->errString      = "不能连接数据库！";
            $this->debugString = "不能连接数据库: ".mysql_error();
            $this->showErr();
            return false;
        }
        else
            return true;
    }

    /* 选择数据库 */
    function _db_select()
    {


        $selectFlag = @mysql_select_db($this->dbname,$this->connid);
        if (false == $selectFlag)
        {
            $this->errCode = 2;
            $this->errString   = "不能选择数据库！";
            $this->debugString = "不能选择数据库: ".$this->dbname;
            $this->showErr();
            return false;
        }
        else
            return true;

    }

    /* 数据库查询语句 */
    function _query()
    {


        $this->resultid = @mysql_query($this->query,$this->connid);
        if (false == $this->resultid )
        {
            $this->errCode = 3;
            $this->errString   = "数据库查询语句错误！";
            $this->debugString = "数据库查询语句错误: ".$this->query.mysql_error();
            $this->showErr();
            return false;
        }
        else
            return true;

    }

    /* 返回查询记录总数 */
    function _num_rows()
    {

        $this->rows = @mysql_num_rows($this->resultid);

    }

    /* 返回结果数组 */
    function _fetch_array()
    {
        if ($this->errCode != 3)
        {
            $tmpResult = "";
            $i = 0;
            while ($row = mysql_fetch_array($this->resultid,MYSQL_ASSOC))
            {

                $tmpResult[$i] = $row;
                $i++;
            }//end while.

            return empty($tmpResult) ? NULL : $tmpResult;

        }

    }

    /* 显示错误信息 $debugString用于调试，$errString用于给客户显示 */
    function showErr()
    {

        //echo $this->debugString."/n";

    }

    /* 关闭连接，释放内存 */
    function close()
    {
        @mysql_free_result($this->resultid);
        @mysql_close($this->connid);
    }

    function __destruct()
    {
        if($this->connid)
        {

            $this->close();
        }
    }
}
/* 数据库查询类  end*/
?>