Query by Custom Field value Equal to another posts custom field value

Hello,
I am currently working on a site where I have two custom post types:

• Courses
• Semesters

What I have a custom template for the Courses post type using single.course.php method.

For each course page, I display the content of the course post, which in this case is a description of the course.

Next I create a query to display the semesters posts.

Because this site also has regular blog posts, I don’t want the semesters and courses to use regular categories.

So, each course I set up a custom field named course then I set the value to the course number, for example GIT-221

Next I set the same custom field on my semesters post.

In short what I want to happen is that each course custom post, will check the current course post custom field and set it’s value to a variable. Then on the same page, run the loop for the semesters posts, if the semester post, custom field value matches the value of the course, then display them.

Here’s what I have going on right now.

I use the following code to set the value of the course post custom field to a variable

<?php
	 $values = get_post_custom_values("course");
	if (isset($values[0])) {
	 $courseVale = $values[0];
}
?>

Next I run a query to get the semester posts

<?php
			$myVale = (string)$courseVale;

 $querydetails = "
   SELECT wposts.*
   FROM $wpdb->posts wposts, $wpdb->postmeta wpostmeta
   WHERE wposts.ID = wpostmeta.post_id
   AND wpostmeta.meta_key = 'course'
   AND wpostmeta.meta_value =  $courseVale
   AND wposts.post_status = 'publish'
   AND wposts.post_type = 'semesters'
   ORDER BY wposts.post_date DESC
 ";

 $pageposts = $wpdb->get_results($querydetails, OBJECT)

 ?>

<div class="col col-100">
	<?php if ($pageposts):
 foreach ($pageposts as $post):
       setup_postdata($post); ?>

               <h3><?php the_title(); ?></h3>
               <?php the_content(); ?>

 <?php endforeach;
endif; ?>
</div>

If I hard code the wpostmeta.meta_value, it will display correctly, but it needs to be equal to the $courseVale (in other words semester posts have to equal the same value as the course, that the semester posts for only that course display).

What am I doing wrong.