How Do I Retain Dropdown Values To Database?

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ASP.NET

SQL-Server-2008R2

I have two dropdowns with data as:
First:
IdTask TaskName
1 Production
2 Analysis
3 Management
Second:
IdSubTask SubTaskName Id
1 Analysis 1
1 Bug fix 2
2 Dev env 1
2 Analysis 2
2 Documentation 3
3 Test 1
3 Analysis 2

I wrote the query to populate 2nd dropdown according to the selected value from 1st dropdown.

However the prob is i am not able to retain the 2nd dropdown value to the database on button click and i need to write a code like if i select 2 - analysis from 1st dropdown populate 2nd dropdown with:
Dev env
Analysis
Documentation

and wen i select Analysis with id 2 in second dropdown it should fill my database with drpdown 1 value - Analysis and drpdown 2 value - Analysis.

Please help!!

thank you!!