从VB将SQL表导出为Excel时的数据访问

给定下面的代码，显示的错误是未定义类型“DataAccess”。为了删除此错误，我应该将什么导入到VB

Protected Sub ExportPOS(ByVal sender As Object, ByVal e As DirectEventArgs)
              Handles ExportButton.Click

    Try
    Make Connection

    Dim cnn As DataAccess = New DataAccess(Libatelconnectionstring)
        ........

尝试此例程（来自MSDN）

Public Sub ConnectToAccess()
    Dim conn As New System.Data.OleDb.OleDbConnection()
    ' TODO: Modify the connection string and include any
    ' additional required properties for your database.
    conn.ConnectionString = & _
    "Provider=Microsoft.Jet.OLEDB.4.0;Data source=" & _
    "C:\Documents and Settings\username\My Documents\dbFile.mdb"
    Try
       conn.Open()
       ' Insert code to process data.
    Catch ex As Exception
       MessageBox.Show("Failed to connect to data source")
    Finally
       conn.Close()
    End Try
End Sub