public function getWhereStatement()
    {
        if (empty($this->where)) {
            return false;
        }
        $this->where[0]['operation'] = null;
        $str = '';
        foreach ($this->where as $clause) {
            $str .= trim("{$clause['operation']} {$clause['condition']}");
            $str .= " ";
        }

        return trim($str);
    }