ADO.NET

        Public Function CaixaAberto( _
                                     ByVal TipoDeCaixa As TiposDeCaixas, _
                                     Optional ByVal MostraAbertura As Boolean = False
                                    ) As Boolean
            Dim lRet As Boolean = False
            Dim dtOperação As Date = Nothing
            Dim sq As String = "SELECT * FROM ABERTURAS WHERE TipoDeCaixa=@TIPODECAIXA AND Fechado=False;"
            Dim cn As OleDbConnection = New OleDbConnection(cs)
            Dim cm As OleDbCommand = New OleDbCommand(sq, cn)
            Dim dr As OleDbDataReader = Nothing
            Try
                cn.Open()
                cm.Parameters.AddWithValue("@TIPODECAIXA", TipoDeCaixa)
                dr = cm.ExecuteReader
                lRet = (dr.HasRows = True)
                If MostraAbertura = True Then
                    If lRet = True Then
                        While dr.Read
                            dtOperação = dr("Abertura")
                        End While
                    End If
                    Dim sMsg As String = ""
                    sMsg += "O emissor encontra-se aberto desde " & _
                           dtOperação.Day & "/" & _
                           dtOperação.Month
                    MsgBox(sMsg, vbInfo, App)
                End If
            Catch ex As Exception
                RaiseEvent Erro(ex.Message)
            Finally
                If Not dr Is Nothing Then
                    dr.Close()
                    dr = Nothing
                End If
                If Not cm Is Nothing Then
                    cm.Dispose()
                    cm = Nothing
                End If
                If Not cn Is Nothing Then
                    If cn.State <> ConnectionState.Closed Then cn.Close()
                    cn.Dispose()
                    cn = Nothing
                End If
            End Try
            Return lRet
        End Function

Dim connection As New OleDbConnection("Provider=Microsoft.Jet.OleDb.4.0;Data Source=caminho_mdb")
Dim command As New OleDbCommand("SELECT * FROM nome_tabela", connection)
Dim reader As OleDbDataReader

connection.Open()
reader = command.ExecuteReader()

While reader.Read()
    Console.WriteLine(reader("nome_campo"))
End While

reader.Close()
command.Dispose()
connection.Dispose()

Dim connection As New OleDbConnection("Provider=Microsoft.Jet.OleDb.4.0;Data Source=caminho_mdb")
Dim command As New OleDbCommand("INSERT INTO nome_tabela ( nome_campo ) VALUES ( ? )", connection)

command.Parameters.AddWithValue("@nome_parametro", "valor_parametro")
connection.Open()
command.ExecuteNonQuery()
command.Dispose()
connection.Dispose()