Database Reference
In-Depth Information
This version of the Premiere Products database contains an extra field, Allocated, in the Part table. The
Allocated field stores the number of units of a part that are currently on order (allocated). Figure 9-21 shows
a representation of this database as a collection of objects.
Rep OBJECT
RepNum:
Sales Rep Numbers
LastName:
Last Names
FirstName:
First Names
Street:
Addresses
City:
Cities
State:
States
Zip:
Zip Codes
Commission:
Commissions
Rate:
Commission Rates
302
Customer:
Customer OBJECT; MV
Customer OBJECT
CustomerNum:
Customer Numbers
CustomerName:
Customer Names
Street:
Addresses
City:
Cities
State:
States
Zip:
Zip Codes
Balance:
Balances
CreditLimit:
Credit Limits
Rep:
Rep OBJECT; SUBSET[RepNum, LastName, FirstName]
Part OBJECT
PartNum:
Part Numbers
Description:
Part Descriptions
OnHand:
Units
Class:
Item Classes
Warehouse:
Warehouse Numbers
Price:
Prices
Allocated:
Units
OrderLine:
OrderLine OBJECT; MV
Orders OBJECT
OrderNum:
Order Numbers
OrderDate:
Dates
Customer:
Customer OBJECT; SUBSET[CustomerNum, CustomerName, RepNum]
OrderLine:
OrderLine OBJECT; MV
OrderLine OBJECT
OrderNum:
Order Numbers
PartNum:
Part Numbers
NumOrdered:
Units
QuotedPrice:
Prices
FIGURE 9-21
Object-oriented representation of the Premiere Products database
NOTE
Figure 9-21 shows just one of many approaches to representing objects. However, all techniques have the same general
features.
ll notice the following differences between the collection of objects in Figure 9-21 and the relational
model representation:
You
'
You represent each entity (Rep, Customer, and so on) as an object rather than a relation.
You list the attributes vertically below the object names. In addition, you follow each attribute
by the name of the domain associated with the attribute. A domain is the set of values permit-
ted for an attribute.
