Q129883: PRB: Dynaset, Snapshot, and Table Objects No Longer Available

Article: Q129883
Product(s): Microsoft Visual Basic for Windows
Version(s): 4.00
Operating System(s): 
Keyword(s): 
Last Modified: 02-FEB-2002

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The information in this article applies to:

- 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 
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SYMPTOMS
========

If you try to dimension a Dynaset, Snapshot, or Table object variable and using
DAO 3.0 (Visual Basic version 4.0 data access objects), you will receive this
runtime error:

  User-defined type not defined.

If you replace the Dynaset, Snapshot, or Table object with the Object or
RecordSet type and use methods such as CreateDynaset, CreateSnapshot, or
OpenTable that are tied to the Dynaset, Snapshot, or Table types, you will
receive this error:

  Feature not available.

CAUSE
=====

Visual Basic version 4.0 has replaced the older Dynaset, Snapshot, and Table
objects with a single RecordSet object. This object can take on the attributes
of any of the older three making it much more powerful and flexible.

RESOLUTION
==========

You can resolve this problem one of two ways.

- Replace references to the older objects, while retaining lines of code such
  as these:

         Dim DB As Database
         Set DB = OpenDatabase("Biblio.mdb")

  For example, instead of this old code:

         Dim DS As Dynaset
         Dim SS As Snapshot
         Dim TB As Table

         Set DB = OpenDatabase("Biblio.mdb")
         Set DS = DB.CreateDynaset("Authors")
         Set SS = DB.CreateSnapshot("Authors")
         Set TB = DB.OpenTable("Authors")

  Use this new code:

         Dim DB As Database
         Dim RS1 As Recordset
         Dim RS2 As Recordset
         Dim RS3 As Recordset

         Set DB = OpenDatabase("Biblio.mdb")
         Set RS1 = DB.OpenRecordset("Authors", dbOpenDynaset)
         Set RS2 = DB.OpenRecordset("Authors", dbOpenSnapshot)
         Set RS3 = DB.OpenRecordset("Authors", dbOpenTable)

-or-

- Retain the older syntax and change the Data Access Object (DAO) Type Library
  that your program uses. Although Microsoft recommends the first method for
  future compatibility, using the older syntax is useful for compiling code
  written in previous versions of Visual Basic in version 4.0 with a minimal
  number of changes. To change the DAO Type Library:

  1. Choose References from the Tools menu in Visual Basic.

  2. Clear the Microsoft DAO 3.0 Object Library selection.

  3. Select the Microsoft DAO 2.5/3.0 Compatibility Library.

STATUS
======

This behavior is by design.

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

Steps to Reproduce Behavior
---------------------------

With the Microsoft DAO 3.0 Object Library selected in Tools REFERENCES
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1. Start a new project in Visual Basic. Form1 is created by default.

2. Add a Data Control (Data1) to Form1.

3. Add the following code to the Form1_Click procedure:

     Sub Form1_Click()
        Dim ds As dynaset  'this generates "User-defined type not defined"

        Data1.Databasename = "Biblio.MDB"
        Data1.RecordSource = "Authors"
        Data1.Refresh

        Set ds = Data1.Recordset.CreateDynaset()
        ' If ds is Dim'd as a RecordSet,
        ' this generates "Feature not available"
        ds.Close
        Set ds = Nothing
     End Sub

4. Start the program by choosing Start from the Run menu or by pressing the F5
  key. The 3251 error will be generated on the CreateDynaset line.

Additional query words: 4.00 vb4win vb4all

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

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