FIX: "No rows were affected by the update or delete operation"

The information in this article applies to:

• The Microsoft Foundation Classes (MFC), included with: Microsoft Visual C++ for Windows, version 1.5

SYMPTOMS

When using snapshots with the Microsoft Foundation Class Library database classes, the following error message occurs:

   Warning: ODBC Success With Info, Warning: 0 rows affected by
       update operation (expected 1).
   No rows were affected by the update or delete operation.

CAUSE

This message may occur because of a bug in the ODBC cursor library (ODBCCURS.DLL). In the following scenarios, the cursor library incorrectly handles modifying of fields that have a pre-defined length (such as numeric fields and everything that is not a text field and not a variable length field):

• A field in a table is null and an application changes the field to a non-null value. After the field has been updated to the non-null value, subsequent updates fail.
• A field in a table is non-null and an application changes the field to a null value. After the field has been updated to a null value, subsequent updates fail.

RESOLUTION

Use one of the following techniques to work around the problem:

• Requery after each update. In other words, set the field to null, and requery. Then set the field to non-null and requery, and so on.

        -or-
  

• Use text fields in situations where the data may be changing from null to non-null data or vice versa.

STATUS

Microsoft has confirmed this to be a bug in the ODBC cursor library included in Microsoft Visual C++ version 1.5. The ODBC cursor library included in Microsoft Visual C++ version 1.51 fixes the problem.

REFERENCES

For more information about the cursor library, see the online books in Microsoft Visual C++ version 1.5 or see Appendix G of the ODBC 2.0 Programmer's Reference (ISBN: 1-55615-658-8).