return $wpdb->get_var( $wpdb->prepare("SELECT comment_post_ID FROM $wpdb->comments
WHERE comment_author = %s AND comment_date = %s", $comment_author, $comment_date) );
}
return $wpdb->get_var( $wpdb->prepare("SELECT comment_post_ID FROM $wpdb->comments
WHERE comment_author = %s AND comment_date = %s", $comment_author, $comment_date) );
}