What is transaction?
• Database frequently store information that describe the current state of an
enterprise. For example, a bank’s database stores the current balance in each
depositor’s account.
• When an event happen in the real world that changes the state of the enterprise,
a corresponding change must be made to the information stored in the database.
With online DBMSs, these changes are made in real time by programs called
transactions, which execute when the real world even occurs.