Transaction Control

You can use two methods to specify the boundaries of transactions with SQL statements. In the most common method,
you specify the start of a multistatement transaction by executing the BEGIN WORK statement. In databases that are created
with the MODE ANSI option, no need exists to mark the beginning of a transaction. One is always in effect;
you indicate only the end of each transaction.

In both methods, to specify the end of a successful transaction, execute the COMMIT WORK statement. This statement tells the database
server that you reached the end of a series of statements that must succeed together. The database server does whatever is necessary
to make sure that all modifications are properly completed and committed to disk.

A program can also cancel a transaction deliberately by executing the ROLLBACK WORK statement. This statement asks the database
server to cancel the current transaction and undo any changes.