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, see SQLSetConnectAttr in the Microsoft ODBC API Reference at  http://msdn.microsoft.com/en-us/library/ms713605.aspx.

Many aspects of the connection can be controlled through the connection parameters. For information, see Connection parameters.