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

• Professional and Enterprise Editions of Microsoft Visual Basic, 16-bit and 32-bit, for Windows, version 4.0

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.

   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:

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.