关于thinkphp多数据库连接的问题

$DSN = array(
   'dbms' => 'mysql',
   'username' => 'root',
   'password' => 'link@13579',
   'hostname' => '192.168.10.70',
   'hostport' => '3306',
   'database' => 'db_linktoo',
  );
  $tootoo = new Db($DSN);
  //$school->switchConnect(1);
  $tootoo->table("link_t_machine");
  $main_account = $_GET ['main_account'];
  $map['UUID'] = $main_account;
  //$sql = "SELECT COUNT(*)  FROM `link_t_machine` WHERE UUID = '".$main_account."' ";
  $total = $tootoo->where($map)->count();


看看我这样操作错误在哪里，请帮我解决，谢谢

在线等啊 ....各位i