criar grafico

Nao estou a conseguir criar um grafico circular  que me mostre o valor que foi gasto em cada produto que um determinado utilizador comprou

<div id="chart-container">
 <canvas id="mycanvas"></canvas>
 </div>
<script>
	$(document).ready(function(){
	$.ajax({
 url: "data.php",
 method: "POST",
 type : 'nif',
 success: function(data) {
 console.log(data);
 var nome = [];
 var descricao = [];

 for(var i in data) {
 nome.push("Player " + data[i].nome);
 descricao.push(data[i].descricao);
 }

 var chartdata = {
 labels: player,
 datasets : [
 {
 label: 'Player Score',
 backgroundColor: 'rgba(200, 200, 200, 0.75)',
 borderColor: 'rgba(200, 200, 200, 0.75)',
 hoverBackgroundColor: 'rgba(200, 200, 200, 1)',
 hoverBorderColor: 'rgba(200, 200, 200, 1)',
 data: score
 }
 ]
 };

 var ctx = $("#mycanvas");
 var barGraph = new Chart(ctx, {
 type: 'bar',
 data: chartdata
 });
 },
 error: function(data) {
 console.log(data);
 }
	});
}); </script>

<?php

//setting header to json

header('Content-Type: application/json');
require_once ('../configurations/config.php');

//database $id=$_POST['nif'];

//get connection

$mysqli = new mysqli(DB_HOST, DB_USER, DB_PASSWORD, DB_DATABASE);

if(!$mysqli){
	die("Connection failed: " . $mysqli->error);
}

//query to get data from the table

$query = sprintf("SELECT reservas.idreserva,servicos.id,servicos.nome,servicos.descricao,reservas.quantidade,servicos.precosiva,servicos.descontos,servicos.iva,servicos.valordesc,servicos.valoriva,servicos.precototal FROM servicos INNER JOIN reservas ON servicos.id=reservas.id_servico where reservas.id_user='$id'");

//execute query
$result = $mysqli->query($query);

//loop through the returned data

$data = array();
foreach ($result as $row) {
	$data[] = $row;
}

//free memory associated with result
$result->close();

//close connection
$mysqli->close();

//now print the data
print json_encode($data);