public function getValue($sql, $input_array=array(), $which_connection='')
    {
        $res = $this->execute($sql, $input_array, $which_connection);
        if ($res && $this->numRows($res) > 0) {
            $row = $this->fetchRow($res);
            return $row[0];
        } elseif ($res && $this->numRows($res) == 0) {
            return false;
        } else {
            if ($this->throw_on_fail) {
                throw new \Exception('Record not found');
            } else {
                return false;
            }
        }
    }