Question

Why does Figure 4 show only one cash resource entity if Fred’s Train Shop uses a general operating checking account for purchases of inventory, supplies, and operating expenses such as rent but also uses a separate imprest checking account for payroll?

Figure 4 is the image below: Integrated REA Diagram for Fred's train shop

Suppliers * Order Inventory Take Customer >O Order + Customer Employees Inventory Employee (Salesperson) Receive Inventory Sales Customer Supplier Employee (Cashier) # Disburse Cash Cash + Receive Cash # Employee (Cashier) Employees las Payee) * Time Worked Employee Time Employee H (Supervisor)

Take a look at Figure 4 and Table 1. Why do the Inventory, Cash, Customers, and Suppliers agent & resource tables all have an attribute that contains data about the balance at the beginning of the current fiscal period?

Answer 1

REA models do not represent actual physical accounts but types of accounts.  Thus, even though Fred’s Train Shop uses two checking accounts, the REA displays a single entity for cash.  This entity contains information about all of Fred’s individual checking accounts.  Each row in the cash table for Fred’s train shop would provide information about a specific checking account.  Each account would have its own primary key.

Then, when there is a cash disbursement it would be linked to the specific record or row in the cash table that represented which of the two checking accounts for Fred’s Train Shop was used to make a particular disbursement. This linking would involve using the primary key of the appropriate checking account as a foreign key in that row in the Disburse Cash event table.

The reason that all three entities contain an attribute that stores the beginning balance is that the related event tables typically contain information for only the current year. Thus, the beginning balance attribute represents information about prior years’ events.

This information about beginning balances is needed in order to calculate current balances at any point in time. For example, the Inventory table would show the quantity on hand for each inventory item at the beginning of the current fiscal year. The M:N table linking the Receive Inventory and Inventory tables includes an attribute for the quantity received of a specific inventory item. The M:N table linking the Inventory and Sales tables includes an attribute for the quantity sold of a particular item. Thus, the quantity on hand at a particular point in time equals the beginning quantity on hand plus the sum of all receipts of that inventory item minus the sum of all sales of that item.

The Customer and Supplier tables contain information about the beginning balances of Accounts Receivable and Accounts Payable for specific customers and suppliers, respectively. Current balances can then be computed by adding the sum of all sales to a customer (purchases from a supplier) and subtracting the sum of all payments from a customer (payments to a supplier) during the current fiscal year.