php - Getting empty data in AJAX after POST -

i'm building trading system , i'm using php data, when arrives empty. it's first time use ajax , don't know doing wrong. here code:

script:

$(document).ready(function() {      $('#submit').click(function(){          //get values         var amount     = $('#amount').val();         var       = $('#from').val();         var         = $('#to').val();          var params = 'select * yahoo.finance.xchange pair in ("' + + +'")';         console.log( params );         $.ajax({             type: "post",             url: "currencies.php",             data: params,             success: function(data){                 $('#result').html(data);                 alert(data); //i'm alerting because not receiving nothing @ #result              }         });     }); }); 

php:

$base_url = "http://query.yahooapis.com/v1/public/yql";  $yql_query = $_request['params']; $yql_query_url = $base_url . "?q=" . urlencode($yql_query) . "&format=json" . "&env=http://datatables.org/alltables.env";  $session = curl_init($yql_query_url); curl_setopt($session2, curlopt_returntransfer,true); $json = curl_exec($session);  $phpobj =  json_decode($json); $conversiones = $phpobj->query->results->rate; $title = new arrayobject();   $title = "$conversiones->name";  echo $title; 

i typed:

params=select%20*%20from%20yahoo.finance.xchange%20where%20pair%20in%20("mxnusd") 

in url, see if php file working , is. echoes name of currencies, not received in script.

thanks in advance.

edit: fixed typos.

you need send key/value pair. sending value without params key.

the key using in php $_request['params']

look in browser console network tab , won't see same url manually put in address bar

try

  $.ajax({         type: "post",         url: "currencies.php",         data: {params: params}, // object key/value         success: function(data){             $('#result').html(data);             alert(data);           }     }); 

also note can print json without echo in php. otherwise json parse error in ajax

just fyi - can make same request directly yahoo right browser without proxy in php on server. see yql console