Page 101 - Accounting Information Systems

72 PART I Overview of Accounting Information Systems

FI GU RE
2-30 BACKUP AND RECOVERY PROCEDURES FOR DATABASE FILES

Backup Backup
Transaction Master
Program Master

Update
Program
Recovery
Program

approach with a simplified sales order system such as that used in a department store. Key steps in
the process are:
The sales department clerk captures customer sales data pertaining to the item(s) being purchased
and the customer’s account.
The system then checks the customer’s credit limit from data in the customer record (account
receivable subsidiary file) and updates his or her account balance to reflect the amount of the
sale.
Next the system updates the quantity-on-hand field in the inventory record (inventory subsidiary
file) to reflect the reduction in inventory. This provides up-to-date information to other clerks as
to inventory availability.
A record of the sale is then added to the sales order file (transaction file), which is processed in
batch mode at the end of the business day. This batch process records each transaction in the sales
journal and updates the affected general ledger accounts.
You may be wondering at this point why the sales journal and general ledger accounts are being pro-
cessed in batch mode. Why not update them in real time along with the subsidiary accounts? The answer
is to achieve operational efficiency. We now examine what that means.
Let’s assume that the organization using the sales order system configuration illustrated in Figure 2-31
is large and capable of serving hundreds of customers concurrently. Also assume that 500 sales terminals
are distributed throughout its many large departments.
Each customer sale affects the following six accounting records:
Customer account receivable (Subsidiary—unique)
Inventory item (Subsidiary—almost unique)
Inventory control (GL—common)
Account receivable control (GL—common)
Sales (GL—common)
Cost of good sold (GL—common)

To maintain the integrity of accounting data, once a record has been accessed for processing, it is
locked by the system and made unavailable to other users until its processing is complete. Using the
affected records noted here as an example, consider the implications that this data-locking rule has on the
users of the system.
When processing a customer account receivable subsidiary record, the rule has no implications for
other users of the system. Each user accesses only his or her unique record. For example, accessing John