Under normal circumstances, it shouldn't matter - because it's a very good idea to use a
Using
block around the creation of the instance anyway:
Using con As New SqlConnection(Acc.Common.Configuration.Instance.ConnectionString)
con.Open()
Using com As New SqlCommand("SELECT iD, description FROM myTable", con)
...
End Using
End Using
Because it ensures that the connection is always closed and Disposed when you are finished with it.
Because you create it, open it, and use it - then the system automatically closes and disposes of it there isn't any problem.
But...if the connection is open when you call Open on it, it will throw an InvalidOperationException