MDAC 2.5 SDK - ODBC Programmer's Reference
Chapter 11: Retrieving Results (Advanced)
Bookmarks can be used to identify data to be updated in the result set, deleted from the result set, or fetched from the result set to the rowset buffers. These operations are performed by a call to SQLBulkOperations with an Option argument of SQL_UPDATE_BY_BOOKMARK, SQL_DELETE_BY_BOOKMARK, or SQL_FETCH_BY_BOOKMARK. The bookmarks used in these operations are stored in column 0 of the rowset buffers. When updating by bookmark, the data that result set columns are updated to is retrieved from the rowset buffers. For more information, see "Updating Data with SQLBulkOperations" in Chapter 12, "Updating Data."