public function having($column, $comp = '=', $value = null, $boolean = 'and')
    {
        if (!$this->isComporaisonOperator($comp)) {
            $value = $comp;
            $comp = '=';
        }

        if (is_null($this->havin)) {
            $this->havin = '`'.$column.'` '.$comp.' '.$value;
        } else {
            $this->havin .= ' '.$boolean.' `'.$column.'` '.$comp.' '.$value;
        }

        return $this;
    }