PRB: Bookmarks Are Not Persisted or Marshalled

• ActiveX Data Objects (ADO), versions 1.5, 2.0, 2.1 SP2
• Microsoft Visual Basic Enterprise Edition for Windows, version 6.0

SYMPTOMS

After a recordset has been reopened, once persisted to disk or marshalled across processes or computer boundaries, the bookmarks are no longer correct and they appear to be reset.

CAUSE

Bookmarks are not preserved when a recordset is persisted to a file with the Save method or when marshalled across processes or computer boundaries.

STATUS

This behavior is by design.

MORE INFORMATION

NOTE: This sample code was written for ADO 2.0 and later. ADO 1.5 does not support a Save method.

Steps to Reproduce Behavior

1. Start Visual Basic.



2. Add a project reference to the Microsoft ActiveX Data Objects Library.



3. Paste the following code in the default forms Load method:




      Dim oRs As ADODB.Recordset      
      Set oRs = New ADODB.Recordset

      With oRs
       .CursorLocation = adUseClient
       .CursorType = adOpenStatic
       .LockType = adLockBatchOptimistic
       .Fields.Append "c_col1", adChar, 2
       .Fields.Append "c_col2", adChar, 2
       .Open
      End With

      oRs.AddNew
      oRs(0) = "1"
      oRs.Update
      oRs.AddNew
      oRs(0) = "2"
      oRs.Update
      oRs.AddNew
      oRs(0) = "3"
      oRs.Update
      oRs.MoveFirst

      Debug.Print oRs.RecordCount
      Debug.Print oRs.Bookmark

      'Delete the first row, move to the new first row, and check its book
      'mark value.
      oRs.Delete
      oRs.MoveFirst
      Debug.Print oRs.Bookmark

      'The Save method can not overwrite existing files.
      On Error Resume Next
      Kill "C:\mytmp.txt"
      On Error GoTo 0

      oRs.Save "C:\mytmp.txt"
      oRs.Close
      Set oRs = Nothing

      'Re-open persisted file and check the first row's bookmark.
      'Prior to persisting the recordset the first row's bookmark was a 2.

      Set oRs = New ADODB.Recordset
      oRs.Source = "C:\mytmp.txt"
      oRs.Open
      oRs.MoveFirst
      Debug.Print oRs.Bookmark
      Debug.Print oRs.RecordCount
      Debug.Print oRs(0)

      Unload Me 

4. From the View menu, choose Immediate Window.



5. Press the F8 key repeatedly to step through the code.

REFERENCES

For additional information about ADO Recordset Properties, please see the following article in the Microsoft Knowledge Base:

Q185423 Most ADO Recordset Properties are not Marshalled

Additional query words:

Keywords : kbADO kbADO150 kbADO200 kbDatabase kbGrpVBDB kbGrpMDAC kbDSupport kbADO210sp2
Version : WINDOWS:1.5,2.0,2.1 SP2,6.0
Platform : WINDOWS
Issue type : kbprb