sql update random number

if (empty($_SESSION['last_read_topic']) || $_SESSION['last_read_topic'] != $topic)

{
    $smcFunc['db_query']('', '
        UPDATE {db_prefix}topics
        SET num_views = num_views + 99
        WHERE id_topic = {int:current_topic}',
        array(
            'current_topic' => $topic,
        )
    );

    $_SESSION['last_read_topic'] = $topic;
}

in line... SET num_views = num_views + 99

how i random number between 1-99

thank you so much

i have answer thank you http://stackoverflow.com/users/3349551/nodisplayname

SET num_views = num_views + ROUND(((99-1-1) * RAND() + 1), 0)