php mysql数据库类(php新手入门)

//by http://www.jb200.com
class mysql{
    private $result;
    private $conn;
    public static $hasNew = false;
   
    private __construct(){}
    function __destruct(){
        self::$hasnew=false;   
    }

    function doNew(){
        if(self::$have_new){
            exit('数据库只能连接一次！');
        }else{
            self::$hasNew=true;
            return new self;   
        }
    }
   
    private function connect($host,$user,$password,$dbname,$charset='utf8'){
        $this->conn = mysql_connect($host,$user,$password) or exit('错误码：'.mysql_errno(). '数据库连接失败：'.mysql_error());
        mysql_select_db($dbname,$this->conn) or exit('错误码：'.mysql_errno().'选择数据库失败：'.mysql_error());
        mysql_query("set names $charset",$this->conn);   
    }

    function query($sql,$buffer=true){
        //mysql_real_escape_string($sql,$this->conn);//特殊字符义
        if($buffer){
            $this->result=mysql_query($sql,$this->conn) or exit('错误码：'.mysql_errno().'sql语句执行失败：'.mysql_error());
        }else{
            $this->result=mysql_unbuffered_query($sql,$this->conn) or exit('错误码：'.mysql_errno().'sql语句执行失败：'.mysql_error());
        }
    }
   
    function getRecord(){
        return mysql_fetch_array($this->result);
    }
   
    function close(){
        mysql_free_result($this->result);
        mysql_close($this->conn);
    }

}

//数据库
$db_host='localhost';
$db_user='root';
$db_pwd='root';
$db_name='news';
$charset='utf8';
$sql="select * from news_base";

$db=mySql::doNew();
$db->connect($db_host,$db_user,$db_pwd,$db_name,$charset='utf8');
$db->query($sql);
while($row=$db->getRecord()){
    echo $row[1].'<br />';   
}