Find data of selected node inTreeview control from Database

Question

Using ASP.NET

I have populated parent-child node from table A on Page_Load():
ID Name    ParentID
1   AA            NULL
2   BB            NULL
3   AA1             1
4   AA2             2

In this way, my tree node is organized. Now I want to read ID of selected multiple node. The need to store selected IDs to another table B. Like:

Code      ID
AG001   3
AG001   4

How to fetch selected node data from Table A then insert into TABLE B along with Code?

Please help.