DOCUMENT:Q217216  18-JUN-2001  [visualc]
TITLE   :FIX: Assertion Or Failure With CDaoDatabase::CreateRelation Meth
PRODUCT :Microsoft C Compiler
PROD/VER::6.0,6.0 SP3
OPER/SYS:
KEYWORDS:kbservicepack kbDAOsearch kbMDAC kbVC kbVS600sp2 kbVS600SP1 kbVS600sp3 kbVS600sp3fix kb

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-------------------------------------------------------------------------------
The information in this article applies to:

 - Microsoft Visual C++, 32-bit Enterprise Edition, version 6.0 
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SYMPTOMS
========

A GPF or assertion occurs when using CDaoDatabase::CreateRelation method against
Access 2000 database with Visual C++ version 6.0.

CAUSE
=====

Microsoft confirms that this behavior is due to a bug in the
CDaoDatabase::CreateRelation() method in DAO 3.6. The implementation of this
method can be found in Daocore.cpp.

In the CDaoDatabase::CreateRelation() method, a DAOFields pointer and a DAOField
pointer is declared. In addition, the DAOFields collection is looped through,
and the DAOField pointer is used to access a field in the DAOFields collection,
and then release is called. At the end of the method, the following check is
implemented:

   if (pDAOField != NULL)
   	    pDAOField->Release();

Since pDAOField was used as a temporary it is not set to NULL. As a result, the
Release() call draws an assertion in the DAO360.DLL implementation of Release()
stating that Release() was called too many times. Consequently, Release() cannot
set the pointer (pDAOField) that referenced it to NULL.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article.

This bug was corrected in Visual Studio 6.0 Service Pack 3. For more information
about Visual Studio service packs, please see the following articles in the
Microsoft Knowledge Base:

Q194022 INFO: Visual Studio 6.0 Service Packs, What, Where, Why

Q194295 HOWTO: Tell That Visual Studio 6.0 Service Packs Are Installed

Visual Studio 6.0 Service Pack 3 included the DAO 3.60 bits as part of the MDAC
2.1 SP1 stack, which fixes this error.

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

To compile with the MFC run time version of 0x0601 and load DAO 3.60, reference
the following article in the Microsoft Knowledge Base:

   Q236991 PRB: Unrecognized Database Format Error with Access 2000 Database

Additional query words:

======================================================================
Keywords          : kbservicepack kbDAOsearch kbMDAC kbVC kbVS600sp2 kbVS600SP1 kbVS600sp3 kbVS600sp3fix kbGrpDSVCDB _IK kbMDACNoSweep 
Component         : dao
Technology        : kbVCsearch kbAudDeveloper kbVC600 kbVC32bitSearch
Version           : :6.0,6.0 SP3
Issue type        : kbbug
Solution Type     : kbfix

=============================================================================

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