一个简单的mysql类

写一个mysql类： 1.能够链接数据库 2.能够执行sql语句 3.sql语句返回一个结果集并保存到数组中 下边是我写的，重点部分有注释大家看下

<?php
/*
*php的mysql类 created by widuu
*
*/
class Mysql{
private $host;
private $user;
private $password;
private $dbname;
private $db;
private $link;
private $errmsg;

public function __construct($server,$dbuser,$pwd){
$this->open($server,$dbuser,$pwd);
}
private function open($server,$dbuser,$pwd){
$this->host=$server;
$this->user=$dbuser;
$this->password=$pwd;
$this->link=mysql_connect($this->host,$this->user,$this->password) or die("链接数据库失败");
}

public function opendb($database,$charset){//连接数据库
$this->dbname=$database;
mysql_query("set names ".$charset);//设置字符集
$this->db=mysql_select_db($this->dbname,$this->link);
if (!$this->db) {
$this->errmsg="连接数据库错误！";
}
}
public function query($sql) {
$result=mysql_query($sql);
if (!$result) {
$this->errmsg="语句运行错误！";
}else{
$data=array();//申明一个空数组
$arr=new ArrayObject($data);//创建一个数组对象 arrayobject::append这个方法把结果集添加到数组中
while($row=mysql_fetch_array($result)){ //mysql_fetch_array()从结果集中取得关联数组
$arr->append($row);
}
return $arr;
}
}
}
?>