DOC: IsFieldNull() Does Not Accept NULL (173423)

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.