Data Controls :: Change And Update TextBox Value Based On DropDownList Selected Value

I have one dropdown list and two textbox. I am developing a small application for my par tics in which currency name  populate from the data base which are in drop down it will working now.

Now I want when I select currency name from dropdown list the code the and the country name show in the  other textbox value .for example when I select Currency name like UK pound the value show .one show currency code 2 and other country name United state. All text box  value change on changing vale in droupdownlist dynamically means all value dependent on the dropdown list .

All value from the data base  

I  bind three value with the currency name ,id,currency code and country name. because when I change the dropdown list so change value in text box .but I fail to do that.

How to value change in textbox to changing value in dropdown list. I know code show be on the DropDownList1_SelectedIndexChanged but I have no exact code

My data base.table

Id (primary key)Currency NameCurreny codecountyname
1 Bangla Taka3 Bangldash
2 Chines Yan5China

Code
private String strConnection = "Data Source=.SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|Database1.mdf;User Instance=true";
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)

[Code] .....