This member function is not applicable on recordsets that are using bulk row fetching, since such recordsets cannot call Edit, AddNew, or Update. For more information about bulk row fetching, see the article Recordset: Fetching Records in Bulk (ODBC).
If automatic dirty field checking is enabled, CancelUpdate will restore the member variables to the values they had before Edit or AddNew was called; otherwise, any value changes will remain. By default, automatic field checking is enabled when the recordset is opened. To disable it, you must specify the CRecordset::noDirtyFieldCheck in the dwOptions parameter of the Open member function.
For more information about updating data, see the article Recordset: Adding, Updating, and Deleting Records (ODBC).