source: comment/recentcomments.module @ 124

<?php


/**
 * Implementation of hook_menu().
 */
function recentcomments_menu($may_cache) {
  $items = array();

  if ($may_cache) {
    $items[] = array('path' => 'recentcomments', 'title' => t('Recent Comments'),
      'callback' => 'recentcomments_page',
      'access' => user_access('access comments'),
      'type' => MENU_SUGGESTED_ITEM);

  }
  return $items;
}

function recentcomments_page() {
  $result = pager_query(db_rewrite_sql('SELECT c.*, n.title FROM {comments} c INNER JOIN {node} n ON n.nid = c.nid WHERE n.status = 1 AND c.status = 0 ORDER BY c.timestamp DESC', 'c'), variable_get('default_morecomments', 10));
  $output = '';
  while ($comment = db_fetch_object($result)) {
    $output .= theme('recentcomments', $comment, '');
  }
  $output .= theme('pager', NULL, variable_get('default_morecomments', 10));
  return $output; //theme('page', $output);
}

/**
 * Implementation of hook_block().
 *
 * Generates a block with the most recent comments.
 */
function recentcomments_block($op = 'list', $delta = 0) {
  if ($op == 'list') {
    $blocks[0]['info'] = t('Recent Comments');
    return $blocks;
  }
  else if ($op == 'view' && user_access('access comments')) {
    $block['subject'] = t('Recent Comments');
    $block['content'] = theme('recentcomments_block');
    return $block;
  }
}

/**
 * Find a number of recent comments. This is done in two steps.
 *   1. Find the n (specified by $number) nodes that have the most recent
 *      comments.  This is done by querying node_comment_statistics which has
 *      an index on last_comment_timestamp, and is thus a fast query.
 *   2. Loading the information from the comments table based on the nids found
 *      in step 1.
 *
 * @param $number (optional) The maximum number of comments to find.
 * @return $comments An array of comment objects each containing a nid,
 *   subject, cid, and timstamp, or an empty array if there are no recent
 *   comments visible to the current user.
 */
function recentcomments_get_recent($number = 10) {
  // Select the $number nodes (visible to the current user) with the most
  // recent comments. This is efficient due to the index on
  // last_comment_timestamp.
  $result = db_query_range(db_rewrite_sql("SELECT n.nid FROM {node_comment_statistics} n WHERE n.comment_count > 0 ORDER BY n.last_comment_timestamp DESC"), 0, $number);

  $nids = array();
  while ($row = db_fetch_object($result)) {
    $nids[] = $row->nid;
  }

  $comments = array();
  if (!empty($nids)) {
    // From among the comments on the nodes selected in the first query,
    // find the $number most recent comments.
    $result = db_query_range('SELECT c.nid, c.subject, c.cid, c.timestamp, n.title, u.name FROM {comments} c INNER JOIN {node} n ON n.nid = c.nid INNER JOIN {users} u ON c.uid = u.uid WHERE c.nid IN ('. implode(',', $nids) .') AND n.status = 1 AND c.status = %d ORDER BY c.timestamp DESC', COMMENT_PUBLISHED, 0, $number);
    while ($comment = db_fetch_object($result)) {
      $comments[] = $comment;
    }
  }

  return $comments;
}

/**
 * Returns a formatted list of recent comments to be displayed in the comment
 * block.
 *
 * @ingroup themeable
 */
function theme_recentcomments_block() {
  //$items = array();
  $return = "";
  foreach (recentcomments_get_recent() as $comment) {
    $return .= '<div class="recentcomments" style=\'padding-top:0.5em;border-bottom:1px solid #D7D7D7;\'>'.$comment->name.': '.l($comment->subject, 'node/'. $comment->nid, NULL, NULL, 'comment-'. $comment->cid) .' in '.l($comment->title,"node/$comment->nid")." ".t('<em style=\'display:block;\'>@time ago</em>', array('@time' => format_interval(time() - $comment->timestamp))).'</div>';
  }
  return $return.'<div class="more-link">'. l(t('more'), 'recentcomments', array('title' => t('Read the latest comments.'))) .'</div>';
}

function theme_recentcomments($comment, $links = 0) {
  $output  = "<div class=\"comment\">\n";
  $output .= '<div class="node"><h2 class="title">'. l($comment->subject, "node/$comment->nid", NULL, NULL, "comment-$comment->cid") . ' ' . theme('mark', $comment->new) ." in ".l($comment->title,"node/$comment->nid")."</h2></div>\n";
  $output .= '<div class="moderation">'. $comment->moderation ."</div>\n";
  $output .= '<div class="credit">'. t('by !a on %b', array('!a' => theme('username', $comment), '%b' => format_date($comment->timestamp))) ."</div>\n";
  $output .= "<div class=\"body\">$comment->comment</div>\n";
  $output .= "<div class=\"links\">$links</div>\n";
  $output .= "</div>\n";
  return $output;
}


?>