wpdb - get title from posttype

gistfile1.php

<?php
/*-----------------------------------------------------------------------------------*/
/*  wpdb get title from post type
/*-----------------------------------------------------------------------------------*/
$post_type = "project";

$results = $wpdb->get_results( 
	$wpdb->prepare( "
		SELECT post_title 
		FROM $wpdb->posts 
		WHERE post_type = %s 
		ORDER BY post_title ASC", $post_type ) );

// Return result
echo json_encode($results);