RFX_Binary Updates Unchanged CByteArray Data (160073)



The information in this article applies to:

  • The Microsoft Foundation Classes (MFC), when used with:
    • Microsoft Visual C++, 32-bit Enterprise Edition 4.2
    • Microsoft Visual C++, 32-bit Professional Edition 4.2

This article was previously published under Q160073

SUMMARY

The MFC ODBC classes attempt to update the CByteArray data for a record each time you move off that record, even if the data was not changed.

If you have a field that cannot be updated, you may receive an error when the update fails. For example, if your recordset contains a SQL Server TIMESTAMP column, you may see the following error:
Can't update a TIMESTAMP column.
The RFX_Binary() function is incorrectly casting the BYTE* data member of the CByteArray to a CByteArray*. Because of this, the CByteArray data always appears to have been changed since the last update. In the DoFieldExchange() of your recordset class, replace calls to RFX_Binary() with calls to the with RFX_Binary_Fix() function.

The following files are available for download from the Microsoft Download Center:


Rfxbinfx.exe

For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base:

119591 How to Obtain Microsoft Support Files from Online Services

Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help to prevent any unauthorized changes to the file.

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This bug was corrected in Visual C++ version 5.0.

MORE INFORMATION

The RFX_Binary() function is called from within the CRecordset DoFieldExchange() function to handle CByteArray data.

Once you have downloaded Rfxbinfx.exe and run the .exe to extract the RFX_Binary_Fix source code, include RFXBINFX.H in your recordset CPP file.

In your implementation of the DoFieldExchange() function, change each call to RFX_Binary to a call to the RFX_Binary_Fix function.

Modification Type:MinorLast Reviewed:8/5/2004
Keywords:kbbug kbDatabase kbfile kbfix kbVC500fix KB160073 kbAudDeveloper