SQL Server Native Client (SNAC) is not supported beyond SQL Server 2012. Avoid using SNAC in new development work, and plan to modify applications that currently use it. The Microsoft ODBC Driver for SQL Server provides native connectivity from Windows to Microsoft SQL Server and Microsoft Azure SQL Database.
Bookmarks let consumers quickly return to a row. With bookmarks, consumers can access rows randomly based on the bookmark value. The bookmark column is column 0 in the rowset. The consumer sets the dwFlag field value of the binding structure to DBCOLUMNSINFO_ISBOOKMARK to indicate that the column is used as a bookmark. The consumer also sets the rowset property DBPROP_BOOKMARKS to VARIANT_TRUE. This lets column 0 be present in the rowset. The IRowsetLocate::GetRowsAt method is then used to fetch rows, starting with the row specified as an offset from a bookmark.