confidence in the data, data from the system of record should be chosen.

To use an analogy. Suppose you wanted to enter a car race. You have two choices—
drive a Porsche or drive a Volkswagen. Your chances at winning the race are probably
improved by choosing the Porsche. But you can choose the Volkswagen and enter the
race. And who is to say that you might not win with the Volkswagen. However, to
improve your odds of success, you probably would be better off choosing the Porsche.

Fig. 15.1.10 shows the data outside the system of record.

Fig. 15.1.10 Data outside the system of record.

Is Data Updated in the System of Record?

Another interesting issue arises—can data inside the system of record be updated? The
answer is yes—of course, it can. However, there are some considerations when it comes
to the issue of update.

Suppose you have a bank account. Suppose you go and look at your bank account
balance as of 10:13 am. Then suppose at 10:45 am, you make a withdrawal from the bank
account. The withdrawal is transacted immediately. When you reference the amount of
money you have in your bank account, the value can change on a moment by moment
basis. Therefore, you have to reference not only the amount of money in the bank
account but also the moment in time the amount was accurate at.

So, update can be done in the application environment.

Chapter 15.1: The System of Record