While I'm not a security expert, but I guess most of the attacks don't copy the database from the disk directly but use the SQL server for that through injectio

While I'm not a security expert, but I guess most of the attacks don't copy the database from the disk directly but use the SQL server for that through injection. If the SQL server can read your database (which is mandatory if it wants to work with it) then the underlying disk encryption doesn't help.