Someone

        my $query = 'SELECT MIN(post_id) AS id,
    GROUP_CONCAT(
        DISTINCT posted_by
        ORDER BY posted_at DESC
        SEPARATOR \', \'
    ) AS posters,
    DATE_FORMAT(MIN(posted_at), \'%Y-%m-%d\') AS date,
    url,
    GROUP_CONCAT(
        DISTINCT title
        ORDER BY posted_at DESC
        SEPARATOR \', \'
    ) AS titles,
    GROUP_CONCAT(
        CONCAT(DATE_FORMAT(posted_at, \'%Y-%m-%d %H:%i\'), \' <\', posted_by, \'> \', message)
        ORDER BY posted_at DESC
        SEPARATOR \'\n\') AS quotes
            FROM posts
                GROUP BY url '. (defined $show_url ? 'HAVING url = ?' : '') .'
                ORDER BY MIN(posted_at) DESC
                '. $limit;