FIX: Assertion Failure in CFieldExchange::GetColumnType() (135666)
The information in this article applies to:
- The Microsoft Foundation Classes (MFC), when used with:
- Microsoft Visual C++, 32-bit Editions 2.0
- Microsoft Visual C++, 32-bit Editions 2.1
- Microsoft Visual C++, 32-bit Editions 2.2
- Microsoft Visual C++, 32-bit Editions 4.0
- Microsoft Visual C++, 32-bit Editions 4.1
- Microsoft Visual C++, 32-bit Enterprise Edition 4.2
- Microsoft Visual C++, 32-bit Professional Edition 4.2
This article was previously published under Q135666 SYMPTOMS
Using the MFC database classes with the Microsoft SQL Server ODBC driver
versions 2.50.0121 or 2.50.0126 may cause an assertion failure after a call
to SQLNumResultCols() in the CFieldExchange::GetColumnType() function.
CAUSE
This error is caused by a bug in the ODBC driver that is exposed when the
cursor library is used, and happens after calling CRecordset::Requery() and
then trying to edit more than one record.
The following code in Dbrfx.cpp produces the assertion:
#ifdef _DEBUG
SWORD nResultColumns;
AFX_SQL_ASYNC(m_prs,
::SQLNumResultCols(m_prs->m_hstmt, &nResultColumns));
ASSERT(nColumn >= 1 && (long)nColumn <= (long)nResultColumns);
#endif //_DEBUG
::SQLNumResultCols returns 0 in nResultColumns, which causes an assertion
on the next line. This is due to a bug in the driver which sets the number
of columns in the result set to 0. The subsequent call to ::SQLDescribeCol
will also fail with SQL State S1002 "Invalid Column number" regardless of
the column number specified.
RESOLUTION
To work around this problem, use a dynaset instead of a snapshot or get the
2.65.0240 version of the SQL Server driver that is included with Visual C++
5.0.
STATUS
Microsoft has confirmed this to be a bug with the ODBC 2.5 components. This
bug has been fixed in the 2.65.0240 version of the SQL Server driver that
is included with Visual C++ 5.0.
| Modification Type: | Major | Last Reviewed: | 12/8/2003 |
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| Keywords: | kbBug kbDatabase kbfix kbVC500fix KB135666 |
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