BUG: S1000 Error When Sharing Connection in Multiple Threads (175313)

The information in this article applies to:

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

This article was previously published under Q175313

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();
         }
      }
   }

Modification Type:	Major	Last Reviewed:	12/3/2003
Keywords:	kbbug kbDatabase KB175313