MDAC 2.5 SDK - ODBC Programmer's Reference
Chapter 14: Transactions
Applications specify the transaction mode with the SQL_ATTR_AUTOCOMMIT connection attribute. By default, ODBC transactions are in auto-commit mode (unless SQLSetConnectAttr and SQLSetConnectOption are not supported, which is unlikely). Switching from manual-commit mode to auto-commit mode automatically commits any open transaction on the connection.