wordpress or php code to populate a dropdown or select options from a database

<?php  
$posts_rows = $wpdb->get_results( "SELECT ID,post_title,post_name,guid FROM wordpress_posts WHERE post_type='attachment'" );
?>

            <!-- Start Image Drop Down-->
            <select style="width:250px;" id="<?php echo trim($background->id); ?>" onchange="update('<?php echo trim($background->id); ?>')" name="selectedimage">
              <?php
  if ($posts_rows) :
    foreach ($posts_rows as $post) :
?>
              <option value="<?php echo trim($post->guid); ?>" ><?php echo trim($post->post_name);; ?>
              </option>
              <?php
	  endforeach;
  else :
?>
              <option value="">Not Found</option>
              <?php 
  endif; 
?>
            </select>

            <!-- End Image Drop Down-->