Microsoft KB Archive/230131

= FIX: Access ODBC Keyset Cursor Becomes Corrupt After a Delete =

Article ID: 230131

Article Last Modified on 9/22/2005

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APPLIES TO


 * Microsoft Data Access Components 2.1 Service Pack 1
 * Microsoft Data Access Components 2.1

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This article was previously published under Q230131



SYMPTOMS
After deleting a row and doing a MoveNext or MovePrevious, the current record is wrong.

Exhibited behavior indicates that the current record will either become another record from within the recordset or EOF depending on the size of the recordset.



CAUSE
A bug was introduced in MDAC 2.1 affecting the behavior of the Access ODBC Driver keyset cursors.



RESOLUTION
To resolve this problem, upgrade to MDAC 2.1 Service Pack 2 or MDAC 2.5 or later. These versions of MDAC can be obtained from the download section at the following Microsoft Web site:

http://msdn.microsoft.com/dataaccess



STATUS
Microsoft has confirmed that this is a bug in the Microsoft products that are listed at the beginning of this article.

This problem was corrected in MDAC 2.1 SP2.



MORE INFORMATION
The specific MDAC 2.1 DLL causing the problem is odbcjt32.dll.

Version 4.0.3513.00 shipped with MDAC 2.1 that was included with SQL Server 7.0.

Version 4.0.3711.08 of odbcjt32.dll shipped with MDAC 2.1 SP1.

MDAC 2.1 SP1 has shipped with Office 2000 and is downloadable at the MDAC Web site.

The following Visual C++ code in conjunction with the Microsoft sample Northwind database can be used to illustrate the behavior. It assumes that you used the MFC AppWizard to generate a CRecordset-derived class that wraps the Order Details table in nwind.mdb. The recordset must be opened as a CRecordset::dynaset to reproduce the problem: CDBwindSet rs;

rs.Open; rs.m_pDatabase->BeginTrans; rs.MoveNext; rs.Delete; rs.MoveNext; //You are now on the wrong record rs.m_pDatabase->Rollback; rs.Close; The following Visual Basic code in conjunction with the Microsoft sample Northwind database can be used to illustrate the behavior. The cursor type needs to be adOpenDynamic. ADO will degrade to a keyset cursor because the Access ODBC driver does not support dynamic cursors.

It appears that setting the ADO recordset property CacheSize to something other than 1 (the default) causes the bug to not appear: Dim cnNorthwind As ADODB.Connection Dim rsOrderDetails As ADODB.Recordset

Private Sub Form_Load Dim strConn As String Dim strSQL As String strConn = "Provider=MSDASQL;Driver={Microsoft Access Driver (*.mdb)};DBQ=c:\temp\NWind.MDB;" strSQL = "SELECT * FROM [Order Details] ORDER BY OrderID, ProductID" Set cnNorthwind = New ADODB.Connection cnNorthwind.Open strConn cnNorthwind.BeginTrans Set rsOrderDetails = New ADODB.Recordset rsOrderDetails.Open strSQL, cnNorthwind, adOpenDynamic, adLockOptimistic, adCmdText rsOrderDetails.MoveNext MsgBox "Row 2 = " & rsOrderDetails!OrderID & " - " & rsOrderDetails!ProductID rsOrderDetails.MoveFirst rsOrderDetails.Delete rsOrderDetails.MoveNext

'Note you expect to be on Row 2 as before but you are not MsgBox "Row 2 = " & rsOrderDetails!OrderID & " - " & rsOrderDetails!ProductID rsOrderDetails.Close cnNorthwind.RollbackTrans cnNorthwind.Close End Sub

Keywords: kbbug kbfix kbmdac250fix kbqfe kbmdac210sp2fix kbjet kbhotfixserver KB230131

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