Databases Reference
In-Depth Information
CustomerNumber
→
CustomerSoldToName
CustomerSoldToAddressLine1
CustomerSoldToAddressLine2
CustomerSoldToCity
CustomerSoldToState
CustomerSoldToZip
CustomerShipToName
CustomerShipToAddressLine1
ƒƒƒƒƒƒCustomerShipToAddressLine2
ƒƒƒƒƒƒCustomerShipToCity
CustomerShipToState
CustomerShipToZip
CustomerRepNumber
CustomerRepLastName
ƒƒƒƒƒƒƒƒƒƒCustomerRepFirstName
201
ItemNumber
ItemDescription
ItemPrice
InvoiceNumber
→
InvoiceDate
CustomerNumber
OrderNumber
OrderDate
ShipDate
Freight
InvoiceTotal
→
ItemQuantityOrdered
ItemQuantityShipped
ItemQuantityBackordered
ItemAmount
InvoiceNumber, ItemNumber
FIGURE 6-16
Tentative list of functional dependencies for the Holt Distributors invoice
Based on your list of functional dependencies, you may learn that the shipping address for a given customer
will vary from one invoice to another. In other words, the shipping address depends on the invoice number, not
the customer number. A default shipping address may be defined for a given customer in case no shipping address
is entered with an order. However, the address that actually appears on the invoice would depend on the invoice
number. You may also determine that several columns actually depend on the order that was initially entered.
The order date, customer, shipping address, and quantities ordered on each line of the invoice may have been
entered as part of the initial order. At the time the invoice was printed, additional information, such as the quan-
tities shipped, the quantities back-ordered, and the freight charges, may have been added. You may also find that
the price is not necessarily the one stored with the item and that the price can vary from one order to another. Given
all these corrections, a revised list of functional dependencies might look like Figure 6-17.
