MDAC 2.5 SDK - ODBC Programmer's Reference
Appendix G: Driver Guidelines for Backward Compatibility
When an ODBC 2.x application working with an ODBC 3.x driver calls SQLExecDirect, SQLExecute, or SQLParamData, and a searched update or delete statement was executed but did not affect any rows at the data source, the ODBC 3.x driver should return SQL_SUCCESS. When an ODBC 3.x application working with an ODBC 3.x driver calls SQLExecDirect, SQLExecute, or SQLParamData with the same result, the ODBC 3.x driver should return SQL_NO_DATA.
If a searched update or delete statement in a batch of statements does not affect any rows at the data source, SQLMoreResults returns SQL_SUCCESS. It cannot return SQL_NO_DATA, because that would mean that there are no more results, not that there is a result from a searched update/delete that affected no rows.