AQT will start a transaction as soon as you connect to a database
your SQL will only be committed or rolled-back once you explicitly click on the Commit Trans or Rollback Trans items
once you click on Commit Trans or Rollback Trans, a new transaction will be started. Your AQT session will remain in a transaction until Auto Commit is de-selected.
If you change the Auto Commit option when you are signed onto a database, nothing immediately happens:
if you are currently in a transaction, the transaction will not be terminated until you commit or rollback
if you are not currenty in a transaction, one will not be started until you click on Begin Trans
Other Notes on Transactions
if you are doing a large or critical change to your database, it is a good idea to run the change as a transaction. The ability to undo the change can be very useful should the change not do what you want!!
once you have run your SQL, you do not need to decide immediately whether to commit or rollback. You can display the table and run queries to determine whether your change has had the desired effect. Once you have determined this, you can choose whether to commit or rollback.
Note that you should display the table using the same AQT session and connection as the one that made the change. If you display the data using a different AQT connection you may see the unchanged version of the data.
while your transaction is active, the rows you have changed in the database are locked and cannot be updated by other users. In some circumstances, other users will not even be able to display the data. You should not leave your transaction active for any longer than you need to.
If your transaction is active, and your PC or connection to the database fails, your changes will be rolled back. Once you have determined that your changes are OK, you should Commit immediately!
there are number of limitations of transactional control
some databases do not have the ability to rollback DDL statements (Create, Drop, Alter etc). These changes will be run outside of transactional control.
some statements (for instance Oracle Truncate) cannot be rolled back.