Article ID: 175313
Article Last Modified on 12/3/2003
APPLIES TO
- Microsoft ODBC Driver for Microsoft SQL Server 2.0
- Microsoft ODBC Driver for Microsoft SQL Server 3.0
- Microsoft Visual C++ 5.0 Enterprise Edition
- Microsoft Visual C++ 6.0 Enterprise Edition
- Microsoft Visual C++ 5.0 Professional Edition
- Microsoft Visual C++ 6.0 Professional Edition
- Microsoft Visual C++ 6.0 Standard Edition
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:
When you use the Microsoft Data Access Components (MDAC) 2.6 driver, you may receive the following error message:
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: kbbug kbdatabase KB175313
