Q173423: DOC: IsFieldNull() Does Not Accept NULL

Article: Q173423
Product(s): Microsoft C Compiler
Version(s): WINDOWS:4.2,5.0
Operating System(s): 
Keyword(s): kbdocerr
Last Modified: 17-JUL-2001

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The information in this article applies to:

- Microsoft Visual C++, 32-bit Enterprise Edition, versions 4.2, 5.0 
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SUMMARY
=======

The documentation for Visual C++ states the following about the argument for
CRecordset::IsFieldNull():

  pv A pointer to the field data member whose status you want to check, or NULL
  to determine if any of the fields are Null.

According to the documentation, you should be able to pass in NULL to determine
if any of the fields are null.

Beginning with Visual C++ version 4.2, this is not correct. Passing a value of
NULL will cause an exception to be thrown.

MORE INFORMATION
================

You can write a function to check whether any fields are null. Here is what the
function would look like:

     BOOL CYourRecordset::IsAnyFieldNull()
     {
        for (DWORD nIndex = 0; nIndex<=m_nFields-1; nIndex++)
        {
          if (IsFieldStatusNull(nIndex))
               return TRUE;
        }
        return FALSE;
     }

Notice that the IsAnyFieldNull() function uses an undocumented function
IsFieldStatusNull(). This function is in the implementation section of the
CRecordset class so note that the function may change in future releases of MFC.
To write code that is not dependent upon undocumented functions, call
IsFieldNull() for each field member in the recordset instead.

Additional query words: kbDatabase kbMFC kbODBC kbOLDocs kbVC420 kbVC500 kbDSupport kbdse

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Keywords          : kbdocerr 
Technology        : kbVCsearch kbAudDeveloper kbVC420 kbVC500 kbVC32bitSearch kbVC500Search
Version           : WINDOWS:4.2,5.0
Issue type        : kbbug

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