PHP实现的mysql读写分离操作

<?php
/**
* mysql读写分离
*/
class db{
  public function __construct($sql){
    $chestr = strtolower(trim($sql));
    //判断sql语句有select关键字的话，就连接读的数据库,否则就连接写数据库
    if(substr($chestr,0,6)=='select')
    {
      echo 'I am using slave db..<br>';
      $link = mysql_connect("192.168.20.201:3306", "open", "123456") or die("Could not connect: " . mysql_error());
      mysql_select_db("hadoop");
      $result = mysql_query($sql);
      while($row = mysql_fetch_array($result,MYSQL_ASSOC)){
        $data[]=$row;
      }
      //print_r($data);exit;
      echo mysql_get_host_info($link).mysql_get_server_info($link).mysql_get_proto_info($link).mysql_get_client_info().'<br>';
    }else{
      echo 'I am using master db..<br>';
      $link = mysql_connect("192.168.20.195:3306","open","123456") or die("Could not connect: " . mysql_error());
      mysql_select_db("hadoop");
      $result = mysql_query($sql);
      //echo @mysql_affected_rows($result);
      echo mysql_get_host_info($link).mysql_get_server_info($link).mysql_get_proto_info($link).mysql_get_client_info().'<br>';
    }
  }
}
$master = new db("INSERT INTO user (id,name)VALUES (NULL,'100')");
$slave = new db("SELECT * from `user`");

I am using master db..
192.168.20.195 via TCP/IP5.1.73-log10mysqlnd 5.0.8-dev - 20102224 - $Id: 731e5b87ba42146a687c29995d2dfd8b4e40b325 $
I am using slave db..
192.168.20.201 via TCP/IP5.1.73-log10mysqlnd 5.0.8-dev - 20102224 - $Id: 731e5b87ba42146a687c29995d2dfd8b4e40b325 $