Ejemplo de autocomplete con AJAX

Código html:

 $( "#paises2" ).autocomplete({
 source: "paises_lista.php"
 });

Código php:

<?php
include_once 'conexionPDO.php';
$sql = "select * from country where country_id=-1";
$sql = "select country as value from country where country like '%" . $_GET["term"] . "%'";
$resul = $conn->query($sql);
$paises = $resul->fetchAll();
echo json_encode($paises);

productos_autocomplete