PRB: MFC DB Classes Don't Update NULL Field Values to Non- NULL

SYMPTOMS

When the MFC Database classes that come with Visual C++ version 2.0 are used, any field that has a NULL value cannot be updated to a non-NULL value successfully.

After opening a recordset on a SQL Server table that has fields with NULL values, the Edit() and Update() methods of the recordset fail to update the value of the field to a non-NULL value. For example, the following code isn't able to do the update:

   CMyRecordSet rs;
   rs.Open();
   rs.Edit();
   rs.m_Name="Test"; //m_Name allows NULLs and is NULL for current record
   rs.Update();
				

The Update() function doesn't return any error, but the m_Name value is still set to NULL.

   CMyRecordSet rs;
   rs.Open();
   rs.Edit();
   rs.m_Name="Test";  //m_Name allows NULLs and is NULL for current record
   rs.SetFieldNull(&rs.m_Name, FALSE);
   rs.Update();