DOCUMENT:Q153017  18-FEB-2000  [vbwin]
TITLE   :BUG: Invalid Operation After Setting RDC Resultset = Nothing
PRODUCT :Microsoft Visual Basic for Windows
PROD/VER:4.00 | 4.00
OPER/SYS:
KEYWORDS:kbDatabase kbODBCkbbuglist

======================================================================
-------------------------------------------------------------------------------
The information in this article applies to:

 - Microsoft Visual Basic Enterprise Edition for Windows, version 4.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

Executing a refresh method against a remote data control after setting the RDC's
Resultset property to Nothing can cause one of these errors:

   "Invalid operation for forward only cursor"

-or-

   "Unknown error or operation"

CAUSE
=====

This error occurs because setting the ResultSet property to Nothing also causes
the ResultsetType property to be set to 0. Zero is not a valid setting for the
ResultsetType property.

WORKAROUND
==========

To avoid this problem, set the ResultsetType property to the valid value of 1
after setting the Resultset equal to Nothing. For example, the following code
will work correctly and not cause any errors:

      Set MSRDC1.Resultset = Nothing
      MSRDC1.ResultsetType = 1
      MSRDC1.Refresh

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. Microsoft is researching this problem and will post
new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION
================

Steps To Reproduce Problem
--------------------------

1. Start Visual Basic 4.0. Form1 is created by default.

2. Add a single Remote Data control to Form1.

3. Add the following code to the form, making sure to change the OpenConnection
   parameters to match an existing data source:

      Private Sub Form_Click()
         Dim cn As rdoConnection
           Dim rsTemp As rdoResultset

           Set cn = rdoEnvironments(0).OpenConnection("", rdDriverNoPrompt, _
            False, "DSN=MyDSN;database=pubs;uid=sa;pwd=;")
           Set rsTemp = cn.OpenResultset("Select * From Authors;", _
            rdOpenKeyset)
           Set MSRDC1.Resultset = rsTemp
           MSRDC1.Refresh
           Set MSRDC1.Resultset = Nothing
           MSRDC1.Refresh
      End Sub

4. Press the F5 key, or select Start from the Run menu to run the application.
   Click once on the form to execute the code and to see the error.

Additional query words: 4.00 vb4win vb432

======================================================================
Keywords          : kbDatabase kbODBC kbbuglist
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB400Search kbVB400
Version           : 4.00 | 4.00
Issue type        : kbbug

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND.  MICROSOFT DISCLAIMS
ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN NO
EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR
ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF
MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.  SOME STATES DO NOT ALLOW THE EXCLUSION
OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES
SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 2000.