Author Page Display Order

<?php
	$authors = $wpdb->get_results('SELECT DISTINCT post_author FROM '.$wpdb->posts);
	//$authorlink =  the_author_posts_link();
	if($authors):
	foreach($authors as $author):
	?>

		<!-- Begin the first article -->
		<article class="author-<?php the_author_meta('user_login', $author->post_author); ?> author">

			<div class="postimage">
				<a href="/author/<?php the_author_meta('user_login', $author->post_author); ?>/" title="<?php the_author_meta('display_name', $author->post_author); ?>">
				<?php echo get_avatar(get_the_author_meta('user_email', $author->post_author), 350); ?>
				</a>
			</div>

			<div class="authorinfo">
				<h2><?php the_author_meta('display_name', $author->post_author); ?></h2>
				<?php the_author_meta('description', $author->post_author); ?>
				<p><a href="/author/<?php the_author_meta('user_login', $author->post_author); ?>/" title="READ POSTS+">READ POSTS+</a></p>
			</div>

		</article>
		<!-- Closes the first article -->

	<?php endforeach; endif; ?>

I have the above code working great for displaying a author list with detailed information. I’m not really great with working with sql, but I need to display this list by the authors nickname. Right now, it is ordered by ID. Any ideas?

Thanks in advance.
Rich