Where To Place ConnectionString In DA

I designed a DAL (data access layer). This DAL mainly consists of a handfull of methods to call stored procedures. All methods are shared. So no instance generation of the DAL class occurs.

The DAL with it's single class is located in an own project. The connection string is defined in the app-config file of this project.

I want other applications to use the DAL class by referencing the dll generated by the DAL-project. For this reason, I can not any longer define the connection string in the DAL app-config as it is, because the client application determines which database needs to be used.

- Dropping the "shared" keyword of my methods. Create an instance of the DAL class. Add a property for the connection string. When application starts, create one global or multiple local instance/s of the DAL and set it's connection string property.

Comment: I don't like this, because it implies more coding work on the application code side (create instance of class, assign connection string)

- Granting the DAC class access to the connection string defined in the application code by adding a connection string property inside the application code. Thus the DAC class remains "shared".

Comment: I'd need to set a reference from the DAL to the application code during without knowing the application yet. I could try stack tracing or something like that. But it feels to convoluted for me.