We've been testing our plugin solution with CRM on-premises and everything was working with IsolationLevel set to "SandBoxed".
We've just been asked to add some logic that will require us to connect to an external database using ADO.Net. The first attempt we tried didn't work since the IsolationLevel setting was causing the following error: Request for the permission of type 'System.Data.SqlClient.SqlClientPermission' failed. Once we changed the IsolationLevel to "None" the new code worked without issue.
At this point, I have a few questions:
1) Is there any way to connect to a SQL database when the IsolationLevel is set to SandBoxed?
2) If there is a way, which is the preferable approach to take?