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Q139069: FIX: Append-Only on Dynaset Recordsets Forces Read-Only

Article: Q139069
Product(s): Microsoft C Compiler
Version(s): 1.51 1.52 | 2.00 2.10 2.20
Operating System(s): 
Keyword(s): kbDatabase kbMFC kbODBC kbVCkbbuglist kbfixlist
Last Modified: 03-AUG-2001

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The information in this article applies to:

- Microsoft Visual C++, versions 1.51, 1.52, 2.0, 2.1, 2.2 
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SYMPTOMS
========

Opening a recordset as an append-only dynaset leads to an internal application
error when Update() is called to commit an AddNew(). A CDBException is thrown,
and the following error is displayed in the output window of the debugger (DB
tracing enabled):

In Visual C++ 1.5x using the Microsoft Access 2.0 driver:

  

  Error: failure updating record.
  Invalid argument value
  State:S1009[Microsoft][ODBC Microsoft Access 2.0 Driver]

In Visual C++ 2.x using the Microsoft Access 2.0 driver:

  

  Error: failure updating record.
  Invalid argument value
  State:S1009,Native:57,Origin:[Microsoft][ODBC Microsoft Access 2.0
  Driver]

CAUSE
=====

Due to a bug in the MFC code, specifying that a recordset be opened as
append-only results in its concurrency being set to read-only. While the
concurrency is not checked for snapshots, it must be consistent in dynasets with
operations performed on the datasource.

Specifying CRecordset::appendOnly as the third parameter to CRecordset::Open
results in m_bUpdatable being set false. Open calls OnSetOptions where, if
m_bUpdatable is false, the concurrency for the recordset is set to
SQL_CONCUR_READ_ONLY. When Update() is eventually called, the ODBC API SQLSetPos
is invoked to perform the update. Because the operation (SQL_ADD) and locking
mode (SQL_LOCK_NO_CHANGE) do not match the concurrency, SQLSetPos fails.

RESOLUTION
==========

Opening a recordset as append-only has very limited benefits, so to work around
the problem, don't use it. The only real benefit to setting a recordset to
append-only is to inhibit you from calling Edit() on the recordset.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. This problem was corrected in Visual C++ version 4.0
but has not been fixed in the 16-bit version of the compiler. We will post new
information here in the Knowledge Base as it becomes available.

Additional query words: 1.51 2.51 1.52 2.52 2.00 3.00 2.10 3.10 2.20 3.20

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Keywords          : kbDatabase kbMFC kbODBC kbVC kbbuglist kbfixlist
Technology        : kbVCsearch kbAudDeveloper kbVC220 kbVC151 kbVC200 kbVC210 kbVC152
Version           : 1.51 1.52 | 2.00 2.10 2.20
Issue type        : kbbug
Solution Type     : kbfix

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