modify database in connection string

Ok i am ready to take 2 connection string . after that hw can i assign them in my complete application becouse in my application overall iam using one connection string globally in every page i need to add another string in complete application

which is not efffiecient is their any other way to rectify this problem,

Please sir iam sure u can find a answere plz suggest me

Why you think this is ineffecient? What you were doing was ineffecient and making no sense.

Another way is to have a placeholder in the connection string {0} for database name

And then using string.Format you can replace placeholder with the database name

Sorry If u mind me sir,

but i didnt  mean that the way u suggested  is inefficient,

changing my connection string through out the application is inefficient for me nw 

so as u said i can add database name to connection string , can u please send  me any example 

becouse i cannot understand the logic soon

Web.Config

 <add name="constr" connectionString="Data Source=.\SQL2005;Initial Catalog={0};integrated security=true"/>

Code

string constr = string.Format(ConfigurationManager.ConnectionStrings["constr"], "myDb");

hello sir this my connection string which iam assigning in my code behind globally ..... 

Dim constr As String = String.Format(System.Configuration.ConfigurationManager.ConnectionStrings("SoftAssetMgmtConnectionString"), "sysclouds@sam")

        Dim conn As SqlConnection = New SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings("constr").ToString())