Q129286: PRB: Clone Won’t Support All ListFields & ListIndexes Methods

Article: Q129286
Product(s): Microsoft Visual Basic for Windows
Version(s): 4.00
Operating System(s): 
Keyword(s): kbDatabase
Last Modified: 11-JAN-2001

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

- Microsoft Visual Basic Standard Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Professional Edition, 16-bit, for Windows, version 4.0 
- Microsoft Visual Basic Professional Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 16-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows, version 4.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

The ListFields (Dynaset and Snapshot method) and ListIndexes (Table method) used
against a Clone created from a RecordSet object will generate the following
error with the Microsoft DAO 3.0 Object Library:

  Function marked as restricted or uses an OLE type not supported in Visual
  Basic

If you chose the Microsoft DAO 2.5/3.0 Compatibility Library and used DynaSet,
SnapShot or Table objects, the ListFields and ListIndexes method used against a
Clone created from a DynaSet, Snapshot, Table, or RecordSet object will generate
this error:

  Run-time error '3251'
  Feature not available

CAUSE
=====

When a Clone is created from any type of RecordSet object, the resulting Clone
is a RecordSet object -- not the Visual Basic version 3.0 DynaSet, SnapShot, or
Table types. It is not dependent on the type of the object from which it was
created. Because the Clone is a RecordSet, only RecordSet properties and methods
are available.

RESOLUTION
==========

Visual Basic Version 4.0
------------------------

The ListFields and ListIndexes methods are included in Visual Basic version 4.0
for compatibility with earlier versions of Visual Basic. For all RecordSet
objects, Microsoft recommends that you enumerate the Fields or Indexes
collection of the object containing the fields or indexes you want to list.

For Cloned objects, you may need to recode any use of the ListIndexes to
enumerate the Fields or Indexes collection of the object. For more information,
please see the "Examples of Converting Code to Jet Version 2.5" topic in the
Visual Basic version 4.0 Help menu.

Steps to Demonstrate the Correct Alternative to ListFields
----------------------------------------------------------

1. Start a new project in Visual Basic. Form1 is created by default.

2. Add a data control (Data1) to Form1.

3. Set the following properties for Data1.

  Property       Value
  -------------------------
  Databasename   Biblio.MDB
  RecordSource   Authors

4. Add the following code to the Form1_Click procedure:

     Sub Form1_Click ()
        Dim RS As RecordSet
        Set RS = Data1.Recordset.Clone()
        For Each Fld In RS.Fields
           Print Fld.Name
        Next
     End Sub

5. Start the program by choosing Start from the Run menu or by pressing the F5
  key.

STATUS
======

This behavior is by design.

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

Steps to Reproduce Behavior in Visual Basic
-------------------------------------------

1. Start a new project in Visual Basic. Form1 is created by default.

2. Add a data control (Data1) to Form1.

3. Set the following properties for Data1:

  Property       Value
  -------------------------
  Databasename   Biblio.MDB
  RecordSource   Authors

4. Add the following code to the Form1_Click procedure:

     Sub Form1_Click ()
        Dim DS As Dynaset, LF As Snapshot
        Set DS = Data1.Recordset.Clone()
        Set LF = DS.Listfields()
        While Not LF.EOF()
           Print LF("name")
           LF.Movenext
        Wend
     End Sub

5. Start the program by choosing Start from the Run menu or by pressing the F5
  key.

Depending on which DAO Reference you chose under Tools References, you will get
one of the two errors mentioned above.

Additional query words: 4.00 vb4win vb4all

======================================================================
Keywords          : kbDatabase 
Technology        : kbVBSearch kbAudDeveloper kbVB400Search kbVB400 kbVB16bitSearch
Version           : 4.00
Issue type        : kbprb

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

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 1986-2002.