php简单数据库操作类的封装

<?php 
  class conndb{ 
    private $local; 
    private $username; 
    private $pwd; 
    private $db; 
    private $connid; 
    private $code; 
    public function __construct($local,$username,$pwd,$connid,$code,$db){ 
      $this->local=$local; 
      $this->username=$username; 
      $this->pwd=$pwd; 
      $this->connid=$connid; 
      $this->code=$code; 
      $this->db=$db; 
      $this->connect(); 
    } 
    public function connect(){ 
      if($this->connid=="pconn"){ 
        $this->connid=mysql_pconnect($this->local,$this->username,$this->pwd)or die("connect mysql false"); 
      }else{ 
        $this->connid=mysql_connect($this->local,$this->username,$this->pwd)or die("connect mysql false"); 
       
      } 
      mysql_select_db($this->db,$this->connid) or die("connect db false"); 
      mysql_query("set names $this->code"); 
      return $this->connid;                 //返回数据库连接对象 
       
    } 
  } 
class admindb{ 
function executesql ($sql, $connid){ 
  $sqltype = strtolower(substr(trim($sql), 0, 6));  //提取sql语句的类型 
  $rs = mysql_query($sql,$connid);        //执行sql语句  
  if ($sqltype == 'select') {           //如果是select查询 
    $arraydata = mysql_fetch_array($rs);       //返回查询记录集 
    if (count($arraydata) == 0 || $rs == false) { //如果没查询到或发生错误 
      return false;             //返回false 
    } else {                 //否则 
        return $arraydata;          //返回记录集 
    } 
  } elseif ($sqltype == 'insert' || $sqltype == 'update' || $sqltype == 'delete') { //如果执行插入、更新或删除语句 
    return $rs;            //返回语句执行状态，即成功返回true，失败返回false 
  } else { 
    return false;           //如果不是上述查询，则返回false 
  } 
} 
} 
$connobj=new conndb("localhost","root","root","conn","utf8","db_database20");  //实例化数据库连接类 
$conn=$connobj->connect();    //返回连接标识 
$admindb=new admindb();           //数据库操作类实例化 
$res=$admindb->executesql ("select * from tb_demo01",$conn); //调用数据库操作类中方法执行查询语句 
if($res){          //如果返回结果为真，则输出数据 
  print_r($res);     //输出一个数组。 
} 
?>

array
(
  [0] => 1
  [id] => 1
  [1] => php新书上市
  [title] => php新书上市
  [2] => php新书上市啦，希望大家给出宝贵意见
  [content] => php新书上市啦，希望大家给出宝贵意见
  [3] => 2010-10-23
  [date] => 2010-10-23
)