一个MYSQL操作类

<?php 
class DB{     
var $host_addr = "localhost"; 
var $host_user = "root"; 
var $host_psw  = "123"; 
var $db_name   = "test"; 

var $link_id; 
var $query_id; 
var $numRow; 

function DB(){ 
     $this->link_id = @mysql_connect($this->host_addr,$this->host_user,$this->host_psw); 
  if($this->link_id){ 
      @mysql_select_db($this->db_name,$this->link_id) or $this->halt("数据库连接失败！"); 
  }else{ 
      $this->halt("连接服务器失败！"); 
   return false; 
  } 
  return $this->link_id; 
} 
function query($sql){ 
     $this->query_id = @mysql_query($sql,$this->link_id); 
  if($this->query_id){ 
      return $this->query_id; 
  }else{ 
      $this->halt("SQL Error::"); 
   return false; 
  } 
} 
function numRow(){ 
     return $this->numRow = @mysql_num_rows($this->query_id); 
} 
function close(){ 
     return @mysql_close($this->link_id); 
} 
function halt($msg){ 
     echo "<font color=\"#FF0000\">".$msg."</font>"; 
} 

} 
?>