My Connection already open but why the system said it closed?

Question

ExecuteNonQuery requires an open and available Connection. The connection's current state is closed.

Why always the system returns that message?

I have a sub:

Private Sub Initialization()    

    If myCEConnection.State = ConnectionState.Closed Then '--> *1
        Try
            myCEConnection.Open()
        Catch ex As Exception

        End Try
    End If

    Dim reader As SqlCeDataReader
    Dim myCommand As SqlCeCommand = myCEConnection.CreateCommand()

    myCommand.CommandText = "Command goes here"
    Try
        reader = myCommand.ExecuteReader() 
    Catch ex As Exception '--> *2

    End Try

    myCEConnection.Close()
End Sub

And I called that function from this sub:

Public myCEConnection As New SqlCeConnection("Connection String Goes Here")

Private Sub Report()
    If myCEConnection.State = ConnectionState.Closed Then '--> *1
        Try
            myCEConnection.Open()
        Catch ex As Exception

        End Try
    End If

    Initialization()

    myCEConnection.Close()
End Sub

When I try to set a breakpoint to the *1 line, the system returns myCEConnection.State = Open {1}. But when I continue to run the breakpoint, on line *2 I got: ExecuteReader requires an open and available Connection. The connection's current state is Closed.

What's wrong with the code?

Note: Every sub/function on the class always have the If myCeConnection.State = ..... part to check the connection is already open or not. Maybe this caused the problem but I'm not quite sure.

Answer 1

You need to associate the connection and the command:

myCommand.Connection = myCEConnection

Also consider changing your code into something like this:

Dim reader As SqlCeDataReader

Using myCEConnection As New SqlCeConnection("Connection String Goes Here")
  myCEConnection.Open()
  Using myCommand As SqlCeCommand = myCEConnection.CreateCommand()
    myCommand.Connection = myCEConnection
    myCommand.CommandText = "Command goes here"
    reader = myCommand.ExecuteReader()
  End Using
End Using

You don't really need the Try-Catch'es, and my guess is the initial myCEConnection.Open() is throwing an exception, but you never see it because of the Try-Catch.