public function update($table, $columns, $condition, &$params)
    {
        list($lines, $params) = $this->prepareUpdateSets($table, $columns, $params);
        $sql = 'UPDATE ' . $this->db->quoteTableName($table) . ' SET ' . implode(', ', $lines);
        $where = $this->buildWhere($condition, $params);
        return $where === '' ? $sql : $sql . ' ' . $where;
    }