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Q182954: PRB: rdConcurRowver Availability Incorrect in Books Online

Article: Q182954
Product(s): Microsoft Visual Basic for Windows
Version(s): 
Operating System(s): 
Keyword(s): kbGrpDSVBDB
Last Modified: 09-JAN-2000

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The information in this article applies to:

- Microsoft Visual Basic Enterprise Edition for Windows, versions 5.0, 6.0 
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SYMPTOMS
========

Books Online indicates that rdConcurRowVer can be used for a table that has only
an ID or a timestamp. rdConcurRowVer changes to rdConcurValues when opening a
server-side cursor on a table that has only a timestamp or only an ID.

CAUSE
=====

The locktype argument specifies the type of locking used to support concurrency.
If a locktype is not supported, it is changed at run-time. rdConcurRowVer
locktype is only supported on a data source that has a primary key and a
timestamp.

RESOLUTION
==========

If you want to use rdConcurRowVer for a server-side cursor, the table must have
a primary key and a timestamp.

STATUS
======

This behavior is by design.

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

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

1. Create a standard exe in Visual Basic. Form1 is created by default. Under
  Project References, select Microsoft Remote Date Object 2.0.

2. Place two CommandButtons on the form and paste the following code in the
  form:

         Option Explicit
         Dim en As rdoEnvironment
         Dim rs As rdoResultset
         Dim cn As rdoConnection
         Dim sqlstr As String

         Private Sub Command1_Click()
            sqlstr = "select * from tablename"
             Set rs = cn.OpenResultset(sqlstr, rdOpenKeyset, _
                rdConcurRowVer)
         End Sub

         Private Sub Command2_Click()
            If Not (rs Is Nothing) Then
               rs.Close
            End If
            cn.Close
            Unload Me
         End Sub

         Private Sub Form_Load()
           Set en = rdoEnvironments(0)
           en.CursorDriver = rdUseServer
           Set cn = en.OpenConnection(dsName:="datasourcename", _
             Prompt:=rdDriverNoPrompt, _
             Connect:="uid=sa;pwd=;database=PUBS;")
           Command1.Caption = "resultset"
           Command2.Caption = "quit"
         End Sub

3. Replace the datasourcename and the table name above.

4. The table name should be changed to different tables, such as primary key and
  timestamp, to try out the various combinations (just primary key, just
  timestamp, just id, id and timestamp, and none of the above).

5. Run the form and execute the resultset click button. Pause the execution.

6. Select "add watch" from the debug window. Create a watch for rs.

7. When the watch window appears, click the plus sign (+) and look at locktype.
  Note that the only time locktype shows rdConcurRowVer is when the table has a
  timestamp and a primary key.

REFERENCES
==========

"Hitchhikers Guide to Visual Basic & SQLServer" - Fifth Edition pp 430-435
and pp 370-372

Visual Basic 5.0 Enterprise Edition Help files and Books Online under "Choosing
an RDO Cursor Type"

Additional query words: kbRDO kbVBp500 kbVBp600 kbdse kbDSupport kbVBp

======================================================================
Keywords          : kbGrpDSVBDB 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVB600Search kbVB500 kbVB600
Issue type        : kbprb

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