In vb.net project, how to check if SQL connection is still available and end all processing? - vb.net

Question

I have a problem in a vb.net Windows Form project. My company is having network issues and is losing connection between the Windows Form application and the SQL server. When this happens, the application locks up and closes. Before any SQL commands are executed, is there a way to check if the SQL connection is even available?
I've tried using this:
If (cmd.Connection.State <> ConnectionState.Closed)
after the cmd is setup like this:
Dim cmd As SqlCommand
cmd = MSSQL_CONN.CreateCommand
but the state is often Open because the network connection fails after the SQL command was initialized.
I've tried to catch the error like this:
Private m_conn As SqlConnection
Try
m_conn = New SqlConnection(cn_str)
Call m_conn.Open()
Catch e As Exception
MessageBox.Show("Error")
If MSSQL_CONN.TransactionStarted Then
MSSQL_CONN.RollbackTransaction()
End If
End Try
but this has problems because it's trying to do a rollback for any other errors and the rollback throws an error because of the loss of connection state. This also starts a cascade into other timers and background processes that continue to run and try to connect to the SQL server.
I'm hoping there something like
If *SQL connection is even still available* Then
Call m_conn.Open()
Else
*Don't execute any other SQL on this form or any other background forms*
End If

Answer 1

Normally it's best to use a using statement for a connection where the connection is scoped to the method you are working with the database. Otherwise you could create the connection as needed e.g. check the connection state as on error.
Public Class DataOperations
Public Shared Async Function Connection() As Task(Of SqlConnection)
Dim cn As New SqlConnection With {.ConnectionString = "TODO"}
Try
Await cn.OpenAsync()
Return cn
Catch ex As Exception
Return New SqlConnection
End Try
End Function
End Class
Then there is locally scoped where the choice is OpenAsync or Open.
Public Shared Function GetCatagories() As DataTable
Dim dt As New DataTable
Using cn As New SqlConnection With {.ConnectionString = "TODO"}
Using cmd As New SqlCommand With {.Connection = cn}
cmd.CommandText = "TODO"
Try
cn.Open()
dt.Load(cmd.ExecuteReader())
Catch ex As Exception
' decide on how to handle
End Try
End Using
End Using
Return dt
End Function
EDIT:
Public Shared Async Function IsServerConnected() As Task(Of Boolean)
Using cn As New SqlConnection With {.ConnectionString = ConnectionString}
Try
Await cn.OpenAsync()
Return True
Catch ex As Exception
Return False
End Try
End Using
End Function