modify database in connection string

hello sir

thankz for keep on supporting me . my problem is i need to update only the database name in current connection string in web.config at run-time....

and i need to get the server name , uid , pwd , database   from the current connection string and need to change only the database name 

http://www.aspsnippets.com/Articles/Programmatically-Add-or-Update-Connection-String-in-ASPNet-WebConfig-File.aspx

in the above url u r manually assigning the connection string .. which iss not useful to me . 

i need to get the connection string values in my code behind and change the database

so is their any way to modify connection string at run time