php中ajax

function postdata(){
	var params = "";

	params += "&terminal=" +  document.getElementById('terminal').value;
  	$.ajax({
		type: 'POST',
		url: 'bing.php',
		data: params,
		success: function(data){
			var re
sult;

			eval("result=" + data + ";"); 

			alert(result.message);

			   	}

		   });

	}



<?php

define('IN_ECS', true);

define('INIT_NO_USERS', true);

define('INIT_NO_SMARTY', true);



require(dirname(__FILE__) . '/includes/init.php');

require(ROOT_PATH . 'includes/cls_json.php');

	$username ='123';

	$terminal =$_REQUEST['terminal'];

       



if ((DEBUG_MODE & 2) != 2)

{

    $smarty->caching = true;

}



$countsql = "select * from ecs_users where terminal_id='$terminal'";

$res = $GLOBALS['db']->getAll($countsql);

$arr['message']='';

if(count($res)==0)

{ 

	 $sql="update ecs_users  set terminal_id='$terminal' where user_name='$username'";

	 $GLOBALS['db']->query($sql);

	 $arr['message']='绑定成功!';

}else

{

	$arr['message']='阅读器已经绑定!';

}

$json = new JSON;

echo $json->encode($arr);

?>