mysql的操作类

<?php

class db

{

        var $db;

        var $position=0;

        function sub_sql($str)

        {

                global $prefix;

                return str_replace("detest_",$prefix,$str);

        }

        function Sql($str)

        {

                $str=$this->sub_sql($str);

                $result = mysql_query($str);

                $i=0;

                while($row = mysql_fetch_array($result))

                {

                        $str_array[$i]=$row;

                        $i++;

                }

                if(empty($str_array))

                {

                        $str_array=array();

                }

                $this->db=$str_array;

        }