Chapter 7 Problem 7-22, p. 330 Whitlock Department Stores runs a multi user DDMS on a LAN file server. Unfortunately, at the present tinte, tile
DBMS does not enforce concurrency control One Whitlock customer had a balance due of $500
when the following three transactions related to this customer were
processed at about the same time
• Payment of $500
• Purchase on credit of $100
Merchandise retum (credit) of $50
Each of the three transactions read the customer record when
the balance was $500 (1 e, before any of the other transactions
were completed). The updated customer record was returned
to the database in the order shown in the bulleted list above,
a. What balance will be included for the customer after
the last transaction was completed?
b. What balance should be included for the customer
after the three transactions have been processed?