Include custom table in query

Working code:

<?php
global $wpdb;
$date = date("Y-m-d");
$querystr = "
SELECT * 
FROM wp_posts
JOIN wp_ftcalendar_events ON wp_posts.ID = wp_ftcalendar_events.post_parent
WHERE wp_posts.post_status="publish"
AND wp_posts.post_type="post"
AND wp_ftcalendar_events.start_datetime >= '$date' 
ORDER BY wp_ftcalendar_events.start_datetime ASC 
 ";
 $pageposts = $wpdb->get_results($querystr, OBJECT_K); ?>
 <?php if ($pageposts): ?>

  <?php global $post; ?>
  <?php foreach ($pageposts as $post): ?>
      <?php setup_postdata($post); ?>

      <?php $start_date = date_i18n("Y-m-d", strtotime( $post->start_datetime )); ?>

      <?php the_title(); ?><br>
      <?php echo $date; ?><br>
      <?php echo $start_date; ?><br>
  <?php endforeach; ?>

 <?php endif; ?>