PRB: CDBVariant Contains Wrong BOOL Value When Calling CRecordset::GetFieldValue()

ID: Q230491

The information in this article applies to:

Microsoft Visual C++, 32-bit Editions, version 6.0

SYMPTOMS

When calling the CRecordset::GetFieldValue() method that accepts a CDBVariant object as a parameter and the target field in the database is a bit field, the BOOL value (m_boolVal) is incorrect.

RESOLUTION

Use an explicit type other then SQL_C_BIT, such as SQL_C_UTINYINT or SQL_C_SLONG, as the type of variable to bind to.

Please see the More Information for details.

STATUS

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

MORE INFORMATION

The following steps use the SQL Server Pubs database as an example:

Steps to Reproduce Behavior

Create an MFC Single Document Interface project with database header file support.

Create a menu item or button event handler.

Type the following code in the handler and change the connect string to reflect your SQL Server database:


	CDatabase db;
	db.OpenEx(_T("Driver=SQL Server;Server=(local);Database=Pubs;UID=sa;PWD=;"));

	CRecordset rs;
	rs.m_pDatabase = &db;
	rs.Open(CRecordset::forwardOnly, _T("SELECT * FROM authors"));

	CDBVariant varField;
	rs.GetFieldValue(_T("contract"),varField);
	BOOL boolValue = varField.m_boolVal;

Observe the value of boolValue. It will be incorrect.

Workaround

Use SQL_C_UTINYINT or SQL_C_SLONG explicitly in the CRecordset::GetFieldValue() method. Replace the last two lines of the previous code block with one of the following:


	rs.GetFieldValue(_T("contract"),varField,SQL_C_UTINYINT);
	BYTE byteValue = varField.m_chVal;

-or-


	rs.GetFieldValue(_T("contract"),varField,SQL_C_SLONG);
	BOOL boolValue = varField.m_boolVal;

Additional query words: boolean odbc


Keywords          : kbDatabase kbMFC kbODBC kbVC kbVC600 kbGrpVCDB 
Version           : winnt:6.0
Platform          : winnt 
Issue type        : kbprb

Last Reviewed: May 7, 1999