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.
In manual-commit mode, calling SQLFreeHandle on a statement handle with an open transaction causes a rollback of pending changes to the database. Calling SQLFreeHandle on a statement handle always closes any open cursors and discards pending results, freeing all resources associated with the statement handle.