获取Wordpress循环中插入的媒体文件的链接

inside the loop I would like to retrieve the URL of an inserted media file of each post. My attempt was:

<?php if (have_posts()) : while (have_posts()) : the_post(); ?>
  <a href="<?php wp_get_attachment_url(the_ID()) ?>">
    <?php the_title(); ?>
  </a>
<?php endwhile; ?>
<?php endif; ?>

But I can't get it to work. I made sure that there is a file inserted into each post. Furthermore I would like to ask, how it is handled if a post has more than one file.

Thanks!

NOTE: I do mean an inserted file, not a featured image.

    <?php if (have_posts()) : while (have_posts()) : the_post(); 
    if ( $attachments = get_children( array(
    'post_type' => 'attachment',
    'post_mime_type'=>'image',
    'numberposts' => 99,// -1 to get all images
    'post_status' => null,
    'post_parent' => $post->ID
    )));

    //the $attachments will have all the images/media attached or used in your post. You can loop through it an use the data as required.
    foreach ($attachments as $attachment) {

    echo wp_get_attachment_link( $attachment->ID, '' , true, false, 'Link to image attachment' );
    }
    ?>

    <?php endwhile; ?>
    <?php endif; ?>