BUG: CRecordset::Update Fails After Upgrading

• Microsoft Visual C++, 32-bit Editions, versions 4.2, 4.2b, 5.0

SYMPTOMS

After you recompile it with Visual C++ 4.2 or Visual C++ 5.0, an MFC/ODBC application built with Visual C++ 4.0 or 4.1 begins to fail in CRecordset::Update.

CAUSE

MFC 4.2 removes the "FOR UPDATE OF" clause from SELECT statements generated for all CRecordset objects.

Some ODBC drivers depend on this syntax and will fail to process the SQL when it is not found.

RESOLUTION

A member variable CDatabase::m_bAddForUpdate was added in MFC 4.2 to internally control the inclusion of the "FOR UPDATE" clause.

Setting this variable to TRUE before opening the recordset will cause "FOR UPDATE" to be appended to the generated SQL statement.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. We are researching this bug and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

CDatabase::m_bAddForUpdate is an undocumented member of CDatabase and as such is not guaranteed to have the same use or even exist in future versions of MFC.

It is offered for use in this article as a workaround only for this current problem.