There is nothing to do with the SP. It's totally wrong. Since you are selecting the UserName from Database based on the UserName. Here in this case your Input and Output will be similar.
Solution:
After successfull login, store the userid in session. Then display the same UserID wherever you need. Example:
Storing UserID:
if(LoginSuccessFull){
Session["UserID"] = txtUserID.Text.Trim();
}
Showing UserID:
if(Session["UserID"]!=null){
lblDispUserID.Text = (string)Session["UserID"];
}
See similar threads here:
I want to display username on every page[
^]
Asp.Net C#, Show user's name on master page when they login.[
^]
--Amit