Used the following method to move comments in WordPress 3.

Key information needed:

Determine the post ID (comment_post_ID) for where the comment was made. You can determine this from the WordPress Dashboard. In this post, ( 781 is the comment_post_ID.

Determine the post ID (comment_post_ID)for where the comment should go.

Determine the comment ID (comment_ID). There are many ways you could determine this, but you should probably choose something unique to the comment like the comment_author_email that you should be able to get from the comment.

Move the comment:

mysql> UPDATE wp_comments SET comment_post_id=”newcommentpostid” WHERE comment_post_ID=”oldcommentpostid” AND comment_author_email=”commentauthoremail“;

Determine the number of comments where the post has moved to:

mysql> SELECT COUNT(*) FROM wp_comments WHERE comment_post_id=”newcommentpostid“;

Determine the updated number of comments for the post where the comment was originally made:

mysql> SELECT COUNT(*) FROM wp_comments WHERE comment_post_id=”oldcommentpostid“;

Update the counts for each of the posts:

mysql> UPDATE wp_posts SET comment_count=”newcommentcountwhereadded” WHERE id=”newpostid“;

mysql> UPDATE wp_posts SET comment_count=”newcommentcountwhereremoved” WHERE id=”oldpostid“;