public function customWhere($custom, $logicalConnector = 'AND',
            $tablePlaceholder = ':TBL:') {
        if ($this->where && substr($this->where, strlen($this->where) - 1) != '(')
                $this->where .= ' ' . $logicalConnector;
        else if (!$this->where) $this->where = ' WHERE ';

        $this->where .= trim(str_replace($tablePlaceholder, $this->name, $custom));
        return $this;
    }