Establish A Connection When The App Is Launched And Keep The Connection Open Until The App Is Closed?

I'm developing a device app in VB.net that will access a SQL Server database. I need to establish a connection when the app is launched, and keep the connection open until the app is closed. I've done the following:In the Master Module:

Public CNN
As SqlConnection

In the Main menu form load:

CNN =
New SqlConnection(sqlConnString)
CNN.Open()

Then when I want to read from the database:

Dim sqlDR
As SqlDataReader
SQL = "SELECT Name FROM Table"

[code]....

When I run the same code without the global CNN, but rather dim the connection inside the Select function, all works well.