Dynamically create connection string and acees that connection string through code behind C# asp.ne

I have create dynamic database but at the same time I want to save and fetch that connection string in c# asp.net but Unable to do it.
So can you please tell me how to save that dynamically created database connection string and fetch it without using web.config file .

As I tried to modify connection string though web.config file but its wrong way to modify connection string.

Can you please give me other solution to connect to dynamically created database without using web.config as soon as possible.