protected function build()
    {
        $sql = $this->start . "\n"
            . ($this->from    ? $this->from . "\n"    : null)
            . ($this->join    ? $this->join           : null)
            . ($this->set     ? $this->set . "\n"     : null)
            . ($this->where   ? $this->where . "\n"   : null)
            . ($this->groupby ? $this->groupby . "\n" : null)
            . ($this->orderby ? $this->orderby . "\n" : null)
            . ($this->limit   ? $this->limit . "\n"   : null)
            . ($this->offset  ? $this->offset . "\n"  : null)
            . ";";

        return $sql;
    }