Sams Teach Yourself SQL in 21 Days, Fourth Edition

Summary

A transaction can be defined as an organized unit of work. The work done during a transaction is usually a series of operations that depends on previously executed operations. If one of these operations is not executed properly or if data is changed for some reason, the rest of the work in a transaction should be canceled. Otherwise, if all statements are executed correctly, the transaction's work should be saved.

The process of canceling a transaction is called a rollback. The process of saving the work of a correctly executed transaction is called a commit. SQL syntax supports these two processes through syntax similar to the following two statements:

BEGIN TRANSACTION
     statement 1
     statement 2
     statement 3
ROLLBACK TRANSACTION

or