A transaction is the logical unit of work done on one database connection to a database between COMMIT or ROLLBACK statements.
The ROLLBACK statement ends the current transaction and undoes all changes made to the database since the previous COMMIT
In Interactive SQL, you can also execute a ROLLBACK by:
Choosing SQL » Rollback.
In Interactive SQL, executing a ROLLBACK from the SQL menu or the keyboard shortcut does not modify the contents of the SQL Statements pane; however, the Results tab in the Results pane is cleared.