XML from oracle relational tables

[admin]

Hi I need to develop an xml string like this

<question index=1>
<answer>Why Not</answer>
<additional_answer> because </additional_answer>
</question>
<question index = 2>
<answer>OK</answer>
<additional_answer>ok</additional_answer>
<sub_questions>
<sub_question index 1>
<answer>Y</answer>
<additional_answer>ok</additional_answer>
</sub_question>
</sub_questions>
</question>

As you can see the sup_question part does not always show up (only when there is a subresponse.

I have my table structured like this
Tbl_Questions
Question_number
answer
additional_answer
sub_question_number

so for question 1 with no subresponses the data can look like this
Question_number | answer | additional_answer |sub_question_number
1 | Why Not | because | 0

for question 2 with 1 sub repsonse the data looks like
Question_number | answer | additional_answer |sub_question_number
2 | ok | ok | 0
2 | y | ok | 1


I hope I am clear enough. I appreciate any help taht anyone can provide