You use the SQLSetConnectAttr function to control details of the connection. For example, the following statement turns off ODBC autocommit behavior.
retcode = SQLSetConnectAttr( dbc, SQL_AUTOCOMMIT, (SQLPOINTER)SQL_AUTOCOMMIT_OFF, 0 );
For more information including a list of connection attributes, see SQLSetConnectAttr in the Microsoft ODBC Programmer's Reference.
Many aspects of the connection can be controlled through the connection parameters. For information, see Connection parameters.