public function build()
    {
        $value = sprintf("'%s'", $this->value);

        $where = sprintf('WHERE %s %s %s', $this->column, $this->operator, $value);

        $keyword = $this->keyword;

        if (!is_null($keyword)) {
            $where = sprintf(' %s %s', $keyword, $where);
        }

        return $where;
    }