DOCUMENT:Q175313  14-JUN-2001  [odbc]
TITLE   :BUG: S1000 Error When Sharing Connection in Multiple Threads
PRODUCT :Open Database Connectivity (ODBC)
PROD/VER::2.0,3.0,5.0,6.0
OPER/SYS:
KEYWORDS:kbDatabase kbMFC kbODBC kbSQLServ kbVC500 kbGrpDSMDAC kbDSupport kbGrpDSODBC

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

 - Microsoft ODBC Driver for SQL Server, versions 2.0, 3.0 
 - Microsoft Visual C++, 32-bit Enterprise Edition, versions 5.0, 6.0 
 - Microsoft Visual C++, 32-bit Professional Edition, versions 5.0, 6.0 
 - Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

When you share a CDatabase object between multiple threads and use the SQL
Server ODBC driver version 2.65.0240 or later, you may receive the following
error message:

   SQLSTATE: S1000
   [Microsoft][ODBC SQL Server Driver]Connection is busy with the results for
   another hstmt

When you use the Microsoft Data Access Components (MDAC) 2.6 driver, you may
receive the following error message:

   State:37000,Native:16909,Origin:[Microsoft][ODBC SQL Server Driver][SQL
   Server]
   sp_cursorfetch: The cursor identifier value provided (1) is not valid

CAUSE
=====

This error occurs because of a timing conflict in the SQL Server ODBC driver or
MDAC 2.6 driver. If two threads are in the process of calling SQLPrepare(),
followed by a SQLExecute() call, this error may occur.

RESOLUTION
==========

Put CRecordset::Open() calls within a critical section to guarantee that only
one thread is executing a SQL command on the connection at a given time.

On the SQL Server back end, it is recomended that you use different CDatabase
objects for different threads.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft SQL Server driver.



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

Following is a code sample that can cause this error to occur:

Sample code
-----------

      void CDBProblemDlg::OnDoDatabase()
      {
         //Open connection to database
         m_DB.Open();
         CSQLRecordSet rs(&m_DB);

         StartThread(&m_DB);

         if ( rs.Open(CRecordset::dynaset) )
         {
             .
             .
             .
             SQLRecordSet.Close();
         }
      }

         void StartThread(CDatabase * pDB)
      {
         AfxBeginThread(InitThreadProc, pDB, THREAD_PRIORITY_NORMAL);
      }

      UINT CDBProblemDlg::InitThreadProc( LPVOID pParam )
      {
         CDatabase* pDB = (CDatabase*) pParam;
         if (pDB->IsOpen())
         {
            CSQLRecordSet SQLRecordSet(pDB);

            if (SQLRecordSet.Open(CRecordset::dynaset))
            {
               .
               .
               .
               SQLRecordSet.Close();
            }
         }
      }

Additional query words: VC++

======================================================================
Keywords          : kbDatabase kbMFC kbODBC kbSQLServ kbVC500 kbGrpDSMDAC kbDSupport kbGrpDSODBC 
Technology        : kbVCsearch kbSQLServSearch kbAudDeveloper kbODBCSearch kbODBCSQLServ200 kbODBCSQLServ300 kbVC500 kbVC600 kbVC32bitSearch kbVC500Search
Version           : :2.0,3.0,5.0,6.0
Issue type        : kbbug

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

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND.  MICROSOFT DISCLAIMS
ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN NO
EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR
ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF
MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.  SOME STATES DO NOT ALLOW THE EXCLUSION
OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES
SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 2001.